[b-man]

An aftermarket 4.25” crank with 3” mains is readily available to make your 400 into essentially a 455. So there’s an affordable alternative if a naturally aspirated 455 appeals to you for the sake of simplicity.

You’d be spending a few hundred at the very least just to have a good used factory 455 crank brought up to snuff if you did already own a 455. For just a few hundred on top of that you’re in forged aftermarket stroker crank territory to allow the use of the ‘73 400 block already in your possession.