As I recall only way to externally recognize 312 engine is counter bores side of flywheel flange(?) I have 2 292s pro built with 312 cranks built to spin 5500 many years still happy engines. I do recommend tire dyno tuning to maximize power and efficiency and saves them from detonating the pistons, something I wish I did not know about.
What about what I have been told that the 312 crank has a more efficient phasing? Fully understand that it might be erroneous information. I bought a 312 a few years ago with the aim of having a 292 based Y Block with the 312 crank. Someone in its past managed to strip a head bolt thread in the block, and that’s why the gentleman let it go. Not sure if there is a solution for the stripped threads in one head bolt or not, but I didn’t buy it for the block, just the crank.
Our experience is that the 292 has better counterweight phasing. 312 can have strange main bearing wear. Possibly from over counter weighting or poor factory balance. We have had good luck with 312 after professional balancing@@CrippledEagle
I went to the metric rings years ago in other engines and agree with your statement. At one time because they were not as prevalent and I was having custom pistons made anyway I went with available ring bore sizes. You didn’t tell us the bore; a 292 is 3.75” and a 312 is 3.80. What bore size rings did you find readily available for your build…I assuming you would not like to go over .060” on a 292 block.
The bore is 3.820 .070 over, these engine have much thicker cylinder wall than 60's engines. .070 on a 292 is like .040 on 302 ford, blocks with a good sonic sheet can go .110" over. This is part II , go back and watch the intro video and part I for more info@@jamestone265
