balls to the walls 400 build

The 451 build originated with using a 440 crank in a 400 with STOCK slugs.

think about it. they are 100 or more down the hole to start with. The stroke difference is .370. So the piston is moved up .185. So it will stick out about .070 or so.

Won't work if there's any ridge whatsoever, but I suppose you could ream it, and try to clean it up with a hone.

May need to use a special head gasket to get the compression down a bit(.070 cometic or something). You could probably ,mill some off the slugs, but I'm not sure how much they would take.

Valve clearance may be an issue. Lot's of things seem to pop up when trying a "frankenstien" type of build.

Should be cheap. You already have the pistons. 440 cast cranks are virtually free. Skip the balance, and giv'er

Another option.
I did a build on a 400 where I milled the deck down .085. with closed 516's that made the comp 10:1. Ssome port work and a crazy cam, and it will rock. Short stroke motor, so you can wind the crap out of it, in a light little rod project.

Valve clearance was no problem, but geometry(pushrod length etc) was a but of an issue