While the 312 engines are notorious for the camshafts not fitting cleanly into freshly installed cam bearings, that’s typically attributed to the cam holes on  the 312’s being machined from each end with those machining operations meeting somewhere in the middle.  As a result, 312’s are noted for crooked cam tunnels and the subsequent failure for freshly installed ‘stock’ cam bearings to allow the camshaft to simply slide in place.  The factory got around that by having a 0.015” undersize cam bearing and then honing those factory installed bearings to the desired fit.  Those bearings were available for awhile as part numbers B4C-6261-B (frnt), EBY-6263-C (X3), and B6A-6262-B (cntr) to make up a full set.  While that is a 312 nuance, the 272/292 engines were machined on a different machining line and the cam holes are machined in a single operation from one end to the other.  As a result, the 272/292 engines do not have the same camshaft fitment issues as the 312’s.  Like all other engines out there, the 272/292 engines are not immune to other fitment issues.
 
When a 272/292 has a camshaft fitment issue, the cam hole or holes being machined on the small side and/or the cam bearings being slightly thicker than required are suspect areas to examine.  It’s rare for a camshaft journal to be so far oversize that it will cause a fitment issue when everything else checks out okay.  When the specs stack up with a slightly smaller hole in conjunction with a slightly thicker cam bearing and/or a journal size that’s only ½ thousandths larger, then fitment issues can come to the forefront.  This can happen even when all the offending parts are within the variability listed in the specifications.  Bent camshafts are always a possibility but they are rare.  Besides a cam bearing being installed crooked, cocked, and/or damaged when installing them, I find cam holes in the block being machined undersize being the root cause much of the time.  If you deal with BBC engines very much, undersize cam holes seem to be a way of life with those engines.  On those, I’ll simply mic the holes before installing the bearings and address undersized holes before attempting to install the cam bearings.
 
What Paul did with an old camshaft with grooved journals to open up the bearing clearance is an accepted method for fixing that problem.  Scotch brite works too.  On undersized holes, grinding the outside of the bearing appropriately in a crankshaft grinder is also an accepted fix.  Taking the block back to a machine shop to correct the problem will simply have that shop doing ‘old’ grooved camshaft fix or using a bearing knife to carve some additional clearance in the offending bearing(s).  A good number of machine shops will already have those grooved camshafts sitting on a shelf for the various engines.
 
For myself, I will generally leave the rear cam plug out of the block until I have test fit the camshaft in the block and insure that it turns freely.  If the camshaft has difficulty turning or installing all the way in, then I’ll install the camshaft from the rear and determine which cam bearing in particular might be the problem.  Installing the camshaft from the rear may indicate an issue with one of the center cam bearings instead of assuming it’s just a rear bearing problem if only installing the camshaft from the front.  From there the appropriate fix is applied.  This is assuming the camshaft is indeed straight but as I previously mentioned, that’s a rare occurrence but easily verified by just measuring the camshaft while rotating it in a pair of V blocks.

Lorena, Texas (South of Waco)

I don't know about bending a cam, but I snapped a 235 inline six cam many years ago, threw a rod, too.

I broke a cam in a 292 once.  Braking stuff was not that unusual for me back then.  I drove like an idiot. I had no money.  I didn't know what I was doing.  Thankfully, I somehow managed to fix the first two. 

Ted, Would grooves parallel with the cam work as well as angled ones? Would be a lot easier to do!

"FREE SAMPLE"

I had that issue with a 292 recent ly. used a cam core  with a grov in the bearing aria  which makes  the 1 grove a cuter depending on the tight cam bering is where you make the cuter. may sound a bit crude but small amount of clean up, then when cam car is back in place take a block of wood and give the cam a smack. I my case the  new cam went in and turned with ease. learned this trick from a local machine shop

When working with machined surfaces you should never wack anything.

Is there a difference in "whack" and "smack"?  You are supposed to smack/whack the crankshaft flange to check for main bearing clearance on the thrust bearing surfaces.  I know some folks use a long screwdriver to move the crankshaft back and forth, but originally we were taught to smack the crankshaft flange with a rubber mallet.  Never say never.  LOL.  Joe-JDC

JDC

Using a badly worn or discarded camshaft, I prefer a single diagonal cut on the rear journal.  That will provide a longer cutting surface as well as being ‘self cleaning’ as long as that diagonal is cut in the direction in relation to the direction that the ‘modified’ camshaft is being turned within the bearings.  I typically only make a groove in the rear journal and that groove is made at an angle rather than a straight down cut so it has the appropriate sharp cutting edge on only one side of the groove.  Never make these modifications to the camshaft that is going to be run within an engine.  I trust that made sense.

Edited after posting for clarity.  Ted.

Lorena, Texas (South of Waco)

Ted, I take it that the angle groove left in the cam journal has no effect when the engine is running and all the bearings have sufficient clearance to perform as designed.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

The groove is only cut in an old camshaft for a tool to make installing the new camshaft easier.  Not in a running camshaft.  Joe-JDC

JDC