for the 400 1st timer
I agree 2bolt 400 blk.s are definitely stronger, the crank's are weak usually break somewhere in the vecinity of the center saddle/cap. Big main journal's 2.650" , heavy c.weight's,less rpm, w/ a stock crank, maybe 6200. 3.750" stroke is nice, 4.00" stroke is better, just splay the main's. By the time you bore, align,splay,&clearance you got the cost of a new block anyway or close to it. I run a 2bolt w/ a 3.48" stroke stock crank w/ stock rod's, KB piston's, balanced. Work's great, spins to 7200 easy. Have spacer's in the block carries 40psi @ 190degrees temp. on 110 gas. Been together 4 yrs. now, getting ready to tear down for 1st time since built it. With MORE stroke you turn less rev's for more power/efficiecy. that the goal anyway.