My engine is similar to the one you propose. The significant differences are that I have a smaller cam, but potentially better flow (intake and heads). I run a 570 which works great for the street, and with a 91mph quarter mile, not too bad on the strip for a street truck.
The 750 may work, if it has vacuum secondaries but even so, it will be bigger than necessary. You say it won't see much street use. Does that mean it won't be driven much or it will be primarily for racing? Racing is the only place you may actually benefit from the bigger carb.

Here's a "recipe" for your goal:
http://forums.y-blocksforever.com/Topic70388.aspx?#bm70417


Lawrenceville, GA

This really depends on the head and intake flow. Stock heads on a y-block G heads flow around 155 to 160 cfms and the B intake around 170 cfms per runner thus 600 and smaller carbs. Offerings for the 302 flowing more cfms can get away with more carb. porting the iron heads up to 200 cfms say at 500 lift means the intake has to be upgraded as well because the intake will be flowing less than the heads. Here comes the aftermarket, mummert or blue thunder and with the extra air a bigger carb can be used.

-Gary Burnette-

I planned on using reds fenderwell headers on the truck but think i'm going to go with the speedway kit with 2.5 inch pipes to flowmasters or the thrush welded mufflers. As far as the carb goes i've found that fords kinda like a bigger carb. I've run stock 302s with 670s with good resultsthats why i figured a 750 would be a good choice for a hotter similar cubic inch engine

1962 f250 currently heartless
1961 country squire 292 3 speed
1963 galaxie 390 powered
1976 f250 4wd 390 powered

I am thinking more like a 600 or 650 CFM carb. Headers and a large exhaust system will be a big help and will also help gas millage.

I'm lookin for as much bang for my buck as i can get but unfortunately a stroker is'nt in the budget. I'm not very familiar with the how the y block responds to camshafts. Do the smaller mid .400 lift cams really wake them up?

1962 f250 currently heartless
1961 country squire 292 3 speed
1963 galaxie 390 powered
1976 f250 4wd 390 powered

With a .030 312 and mild porting to the heads AND intake I'd keep the cam around say a comp tight lash rated duration 264 @.050 234degrees with a lobe sep around 110 degrees and carb in the 600 to 650 cfms. More cubes and more porting on the heads etc then a bigger cam and carb maybe?

-Gary Burnette-

Hi guys I'm looking for some advice on increasing the performance 312. I have a combo in mind and was hoping to get some feedback from guys more familiar with y's. The base for the build is a 57 312 with the g heads and a b intake. The combo i'm thinking of is .030 over with mummerts pop up pistons on stock rods with a stock crank, i'm looking at mummerts y 292 s camshaft. Mild home port clean up of heads and intake with a 750 holley on top. Its going in my f250 and wont see much street use. I'd like to see 325 horse and 350 lb ft out of this engine. Any advice would be greatly appreciated thanks in advance

1962 f250 currently heartless
1961 country squire 292 3 speed
1963 galaxie 390 powered
1976 f250 4wd 390 powered