If I were to swap my 1990 Mark IV 454 block out for say a gen 5 block, which would already have a hydraulic roller cam, would my 781 heads work? I know the heads I have are adjustable, but I heard the gen 5 heads don't have an adjustable valvetrain.

I want to be able to use my heads and 177 blower, but don't want to have to pay the high $$ for retrofit hydraulic roller lifters etc.

Thanks, and sorry for all the questions. Too much idle time from blown motor provides more time to think about stupid shit