the trans is no problem, it will bolt straight up
the cam on yhe other hand could give you fits
on the A12, the oil pump and the distributor are driven by the same gear, at the front of the camshaft, with the fuel pump mounted aproximatly centered between no.2 and no.3 cylinders
on the A12A A13, A14,and the A15 the distributor is mounted about centered between no.2 and no.3 cylinders (about the same place as where the A12 fuel pump would be) that would leave you with no way to drive the distributor.
IF I remember correctly, you can put a cam from a later one(A12A,A13,A14, A15) as long as you have an electric fuel pump, but putting an A12 cam into the other ones will require an alternitive ignition system