You might be right, most 400 blocks are drill only for 2 bolt mains, the RAM IV used 4-bolt caps and most RAM AIR III I've seen used 2-bolt caps with the block being drill for 4-bolts. I don't have a lot of experience with the 70 blocks. Your enigine should have 13 heads on it from the GTO. Either way it's a great block to have. And you can buy 4-bolt caps for it.
Restoring a 1968 400 4spd, numbers matching Firebird Coupe, Verdoro Green. Larry My old 68. Wish I had her back.
