What will my 70 383 Super Cammando fit in
Nothing a torch, sawzall and a welder can't make work and fix.
The E-body rear is a little wide IIRC, for most A bodies, sorry, all A bodies.
The shifter point of mount is in the wrong spot. It'll take a rear section swap to correct or an adapter plate to adjust it's position.
You could trade the rear for a rear and trans for a trans. E to A body