Howard,
I believe you are keeping the MOTRONIC? I would suggest you contact Richard Clewett, Clewett Engineering for an electromotive system that is compatible with the motronic. You may actualy wind up spending less total money and I guarantee you will get a fabulous product. I "think" that electromotive integrates with the motronic (but Richard will know for sure). At which case you lose your distributor completely. The 3.2 already has a crank position sensor, I'm just not sure that you can tap into that for the electromotive.
As you are single plug, the system is a little less money (just one coil pack and one set of wires plus the ignition box). The box is very high quality and has no issues with being mounted in the engine bay. I took ours apart before I put it in, the entire electronic circuit board is inside of a gel-like substance is probably impervious to anything this side of submarine depth water.
http://www.clewett.com/
Richard Clewett will know the answer and have the parts you need.
As a final comment, let me add that the MSD is a waste of money on your car. It is nowhere near the quality of the stock MOTRONIC system you already have. Sorry. But that is the truth. Your MOTRONIC system is extremely difficult to improve upon. Unless you are getting really crazy with the heads and camshafts (and you aren't) the MSD will give multiple hits below 3,000 and could improve idle and low speed driveability. That is the only possible area of improvement over what you already have. But most people who go to the effort of head/camshaft work on a 3.2 engine go to a twin-plug system which allows (on a 911) about 10 degrees less advance. Less heat, less drag, etc.
angela