a Body / swap to b body.

I would think the engine mounts on both K frames would be the same if they are both 6 cyl cars… BUT there is something about the early/mid 60’s B cars having the engine mounts being further forward, something to watch for if that applies to the sixes.
The engine mounts may be different from late to early years, Spool mounts or biscuit mount will be different depending on what year the /6 is.
B body K is wider than A body where it bolts to the wider frame rails on the ‘64.
Sorry I don't have a definitive answer but thats what I do know (that I can remember) until someone here schools both of us better.
Rustyratrod Im lookin at you.