IMHO Keep your 72 numbers parts to preserve the value of the vehicle. Get the matching EFI brain & EFI wiring to the brain from the donor car. EFI tends to be a little be happier with the matching brain. I went with 3.0 CIS (carbs work well too) in my 73 because it was the least amount of changes. The 3.2 will bolt up but the trans/ring & pinion will be a concern if you like to hot rod the car. Some people have not had issues but others have sheared 7:31 gear teeth because of the increased torque (not peak HP). A 8:31 915 will handle the torque but will probably require a speedo change. The suspension & tire size will also need to be considered if you want to hot rod around. Is it is a matching numbers car? Is it just better to get a later model Carrera for the 3.2 power? Not passing judgment, just saying. Make yourself happy.
