Trans is key before ording the car, ZF's seem to be hard to get as well as most Porsche trans. The clutches for either are not a problem. With the ZF they are cheeper and easier to get, but no shortage of porsche aftermarket suppliers as well. You will need a special flywheel and pilot bearing for Porsche, but other then that both likely the same headache with adapters/bell, axles linkage, etc.
Sandy