You're making this a whole lot harder than you need to. Making yourself crazy for nothing. Here's what I would do: Head over to ebay, you can get an MSD 6A, or 6AL for el cheapo. (6AL has a built in rev limiter, but the 6A is cheaper). If it doesn't come with wiring diagrams,
www.msdignition.com has them online, or ask in here. Not hard to wire at all. And to boot, they work very well with the Duraspark. Actually the Duraspark is an excellent ditzy, until you get into high-end horsepower stuff.
Factory wiring from the car should work with the new Alt. and regulator. Just double check and make sure the wiring is on the correct side, if not make a new harness. Keep this one as short as possible.
Gauges should be OK with the factory harness, just make sure you use senders for the 5.0 With the factory tach, (assuming you'll be using the 5.0 coil) all you need to do is remove the gauge cluster, and there's a little rotary switch on the back of the tach labelled 4-6-8, you guessed it. Spin that sucker over to "8", and reinstall it.
That's the easiest way I know of man. I sold my MSD 6A on ebay for just over $75, so for a little cheddar, you can keep your sanity. Just make sure you have all the wires from the 2.3L cut/capped/sealed. Don't want any shorts causing you headaches in the future.
Good Luck!
