looking for good info for swaps

I have a very straight/clean 68' Valiant 100 /6. I plan to drive it as is for a while then build a low budget sleeper.
I plan to swap to an 8 3/4 rear,manual disc front, big bolt pattern. I am getting a 318/904 combo for free, so I need a V8 k-member.
I need to know from you guys... what makes/models years will interchange with my 68'Valiant.
TIA
Bill