/6 to v8 chassis changes?

73+ spool K members, which are superior to the older style; less prone to ripping engine mounts, sway bar goes through the k member, etc. But the older style has cheaper motor mounts, that you don't have to spend a mint to either buy, or fabricate conversion mounts, and you can swap from a slant to a v8 with your eyes closed.

ALSO, look up 'k-frame reinforcement' for prone issues you need to fix before you get serious with either style.

Frame connectors!

1"+ torsion bars, unless this is a drag-mobile, then /6 bars are what you want.

If your into cornering these can do it well with carefully selected parts.

Do some searching and you will find your answer. Welcome!