I would do, and have twice, what Streetwise suggests, have the crank offset ground on the rod throws to BB Chevy rod size with either 4.250 stroke or 4.300 stroke and have the mains turned down to 383-400 main sizes, also have the counterweights cut down to 7.25 diameter for balancing.My 505 bracket motor has a Ohio Crankshaft CO. 4.25 stroke in a 1971 400 block with Chinese, RPM brand, 6.700 long H beam BB Chevy size rods and Diamond pistons, the other block is in my street Duster with a six bolt flange Chinese crank that was offset ground to 4.300, it has 6.800 long CAT brand BB chevy rods in it with Ross dished pistons for pump gas Both motors are solid roller cam motors with roller rockers, aluminum heads and both make a lot of power. The 440 blocks have a history of breaking the main webs, I have seen or torn two bocks down with broken main webs Not so on any 400 blocks I have seen or heard of on here or anywhere else I did have ductile iron main caps put on both of my stroker 400 and one stroker 440 block, no problems on them so far If you don't want to make over 600 HP you can use either block, over that go with the 400 block 600 HP with a large(500C.I.+) stroker is not hard to do