Engine mount location/ K- frame is the same.64 and 65 models. You'll need to ensure the motor has the brackets.
You will need the V8 Centerlink as mentioned. It has a greater drop to accommodate the oil pan. V8 Torsion bars would be good. They are slightly thicker than the slant 6.
Radiator is different. Double check your inlet and outlet needs. (Center, left, right)
Early A exhaust Manifolds are unique as well.
I like that you're saving the pushbutton. Good luck