Lowest cost 400 stroker

If you have a crank grinder in your area a stock iron headed, factory 3.75" stroke crank 451" is the least expensive. You can use factory rods, etc.

The next step up would be 440 source heads with the springs, guides and valve job checked.

If you wanted more cheap cubes a factory 3.75" crank can be offset ground to 3.915" to make 470" with a 6.535" BBC rod.

If you didn't want to use a factory crank you can go aftermarket at 4.15" or 4.25" stroke/2.200" BBC rod journal with a variety or rods and shelf pistons available. The 4.15" stroke would allow for more oil pickup clearance if you are using an internal oil pump pickup.

The 4.15" stroke crank has a very similar compression height (or CD or CH) to a stock Chevrolet LS3. Nothing to worry about unless you have other problems in my experience.