I recently picked up a '57 Tbird and in going through the engine I found it had cracks in the main webs. I picked up another 312 with a Std bore and unfortunately it also had cracks in the main webs. I then did some research and found this is a common problem with the 312 so think a 292 may be the way at this point my Y-Block knowledge is lacking and I am finding its a steep learning curve so far. I am just looking for a stock rebuild (ie no high performance work) and to that end  my initial questions are-
1. Should I try to get an early or later block? From what I have read, the early blocks have thicker castings around the bore, but the later ones (C1/C2) have stronger main webs.
2. If the early castings have thicker bore castings, what is the max overbore they can handle? Is .060" the max or can they can more. If they can go more, are pistons available for the larger overbore?
3. Is there any problem with using my ECZ-G heads on a 292?
4. Since I have all my 312 innards, should I consider using them on a 292 block? I realize I will need to grind the crank and wonder if it is worth the effort.
5. Are there any other things I should be thinking about as I try to get the Bird back on the road?

TIA for any insight

I agree with everyone’s assessment of the 312 crank in the 292. Pay close attention to the seal area as many use neoprene/ rubber etc instead of the “rope”. The rope needed a different finish from my experience with other engines.

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