You are not going to find "conversion" motor mounts that bolt to a /6 to a small block. The slant 6 brackets that are welded to the K member are entirely different and in the wrong location for a small block, or a big block. You will have to cut the brackets off the K member, then I would weld the brackets to use the spool mounts on the K member you removed the slant 6 motor brackets from.

Also, an A body k member will not fit on a B body. Gene