Hotrod 316:
Two bolt blocks are a lot stronger than most give credit.
We build several Big Block Ford [460 style] engines every year.
Most of them are two bolt main and 800 HP seams to be the line in the sand.
The B.B.Chevy and Ford both have 1/2" main bolts or studs and are very strong.
As with any engine the problems are caused by detonation.
If the engine has pre-ignition and or detonation it doesn't matter how many bolts are holding the main caps down.
We see main cap walk and material transfer with too much timing and engine load.
And it happens no matter if its a Dart block with billet caps or stock.
As far as RPM goes that has no effect on 2 or 4 bolt construction.
The key to high RPM use is light weight parts.
Keep the timing conservative and the mixture a little rich. We are all bracket racing. Make it run forever.
That's my opinion.
Matt Shaff