Ashton -- happens I worked on an ’83, ’84, and ’91 9.9 this summer — know from experience you can switch the whole ignition system from the ’91 to the ‘80s motors (as well as the cylinder head --t.stat more accessible than on earlier ones.) So if you were to find a ’91 electric donor motor, say, you could just make the switch (and include the whole starter assembly, neutral safety switch, etc.) You should be able to do the same thing with any of the 9.9 (or 15) electrics from ’85 to ’91 (actually, probably ‘70s through ‘90s, but would have to look and compare). You will need the rectifier assembly if you want to be able to charge the battery in an electric start system. Your stator is probably the same as or similar to the elec. start models of similar vintage -- would have to look to see what would be involved if just purchasing and wiring in a rectifier. If you have a charging system, the battery should be connected whenever you run the motor.
So if BillP destroys his lower unit, gets mad and sells the motor, you should buy it.