engine and transmission swap

[Dadof3futurejeepers]

I have a inline AMC 258 i6 / 4.2l with a T-150 tranny , my question is which v8 swap will take the least to modify and still use the existing tranny and differential if any?

 

[BusaDave9]

I would go with a AMC 304 V8. They often came with a T-150 tranny and it should fit without too much trouble. If you can find a AMC 304 from a jeep get the bell-housing too.