The 4ac blocks are very similer and probably could be used with 4age parts but a 4age is cheap allready together.
The 4ac heads are were built with economy in mind so there is nothing performance about them, Keep the 4ac head a practise porting on it and if you stuff it up its no loss to the world.
A rwd 4age and 5 speed for $1100 is a pretty good price.
Ae72 would that be similar to a Te72 ?
Ae82 and Ae86 pedal boxes are different, Ke70 and Ae71 pedal boxes are interchangable with each other, Ae86 can also go into a Ke70 and Ae71 but its more stuffing around.