I think I am right about that but can't find anything with a quick search on the internet to confirm this or not.
If so this following information might give some insight into power levels. For a Chevy anyway.
Two bolt main blocks are more common and easier to come by. Many will even argue they are stronger than their four bolt counterparts because they take less material out of the web of the engine block. A two bolt also gives you the option later of installing 4 bolt caps or splayed main caps -- the strongest combination possible. Keep in mind there are significant machine shop labor costs using this option.
If you plan to exceed 400 HP with a small block or 600 HP with a big block, you should use a four bolt block.
If you plan to exceed 500 HP with a small block or 800 HP with a big block, buy a two bolt main block and have splayed caps installed.
Be careful with certain 4-bolt blocks before you buy them, especially the 400 small block Chevy. It is very common for these blocks to be cracked in the web area near the mains.
