2-Bolt mains should be good for around 400 horsepower. I wouldn't try anything above that. I've never seen a hot rod rip the mains out of its engine block, and neither has my good buddy, machinist Ernie Cross. I asked him about it when I bought my block(a two-bolt). He said that in higher horsepower applications, the two-bolt mains can walk and squirm a little bit at high RPMs causing bearing failure. I've gotta take his word for it, he's a smart guy. As for the actual fit of the crank in the block, the oil pan mating faces parallel to the crank have to be notched so that the rod bolts on the longer stroke 400 crank won't whack them. Some more clearancing might have to be done on the bottom of the bores and on the area above the main caps(sort of between the main caps and the cam tunnel). I hope this gives you some idea of what to expect, but you should talk to a machine shop since I've never actually built a stroker motor before. Oh yeah, Is your block one with the one piece rear main seal? If it is, you'll have to buy an adapter to fit the 400 crank into the block since(I think)all 400 c.i. engines used the two piece seal. The shape of the crank is different at the back.
Good Luck, TrustyRusty
