Good question. All the reading I've done so far suggests I should try to find the 906 or 915. The shop can install hard seats for me relatively cheap.I can't argue that. What heads are in your plan?
Buuuuut those 915s are $$$. The engine I have is a 76 400, I think it has the 452s with hardened seats. So possibly a nice valvejob, bowl blend on those? From what I have read the 906 has a better intake port and the exhaust ports between the two are pretty much the same. Very curious your thoughts.