Motor Bracket Question

Jegs sells a motor mount adapter kit to put a small block in a 70- 76 A body 6 cylinder car, So if the early A body 64 to 66 K member is slant 6 or V8. Same K member for either, then you would think the Jegs Slant 6 to V8 adapter kit would work in a early K member.
Am i wrong?
Trans Dapt 4697: Engine Swap Motor Mount Kit Mopar B/RB into 1967-72 Mopar A-Body Chassis with Slant 6 K-Member | JEGS

64-66 K's are narrower than the 67+ years