I just can't slant .....
A friend of mine swapped out a /6 to a 440 in an 80's step side. He bought all the factory mounts, pan, etc. He liked to have never got it to line up right in the truck. Ended up, he had to knock out different holes in the frame where the motor mount insulator goes in.
@318willrun I don't know if the same applies to /6 to small block swaps. The dimples where the insulator goes supposedly just knock thru with a punch and a BFH.