I think Norbie may be right the t18 member most likely bolts in but I haven't confirmed it. The problem you have in doing this is the power steering mounts won't be on the t18 member in which case you will have to weld them on. In my opinion the easiest way is to unstich the engine mount off the ae86 member and re weld in the appropriate place. I have looked into this and it looks like a straight forward and a well worth while conversion. Yes the 4agze may look like a cheap and easy conversion but the FWD/RWD looks like buggering around(cooling/intake) to me and when you have to pay delwo automotive 500+ for a bellhousing to get a half decent box behind it, the 3tgt starts to look attrative to me. The engine era is right 83-85 and if using the orignial efi gear ther should be no problem in getting engineers certificate
by the way if you gze any car that is supposed to be NA then an engineering certificate will be required.