a Body / swap to b body.

If your "B" is a slant six car, the "A" body slant will fit right in. Just swap the required, bolt on pieces from the "B" slant engine onto the "A" slant engine.

FU64RY said

Let me start over.
I have a fresh built 225 / that came out of a 65 date code a body.
I am going to pull the 225 / out of my 64 b body and put the engine that came out of the a body.
I am going to use the b body mounts and put them on the a 225 engine.
If the engines are exactly the same configuration, why would the size of a body and b body K make any difference?

Click to expand...

It doesn't. Any slant six from 1960-1967 will swap out to any other slant six in the same year spread. Any slant six from 1968-1987 will swap out with another slant six with that year spread. A 1968-1987 slant six can be swapped out with a slant six from1960-1967, with a minor adaption for the flywheel/flexplate, and converter hole in the end of the crank. Any other change are related to "bolt on" parts depending on the year and model of the vehicle. A 60-67 slant cannot be easily swapped into a 68 or newer vehicle.
EDIT: There are different oil pans, and pickups, that are vehicle and year specific. You might have to swap these