Ok going thru my 63 Nova and just replaced the HEI distributor with a new ProComp unit that has a working Vacuum Advance, WOW what a difference! Idles 10 times better and doesn't diesel when shutting it off!
But I've worried about the BAT+ wire that runs to the HEI. Its an 18 Gauge wire with a heat sheath around it. Is this enough to run the new 50,000 volt HEI coil? What about running the Electric Choke as well!!??!
My thought is to run a 14 gauge in its place, and crimp a new connector that has two 14 gauge wires, the second one would run to the Electric Choke. Does this sound like a great approach or should I be pulling Electric Choke from somewhere else?
http://63nova.nextmill.net/pics/temp/ignwire.jpg

I imagine that heat shielded wire is in fact a resistance wire. Resistance wire was used on 1st Gen camaros and lots of other vehicles made by GM (and others) through the early 70's. Resistance wire provides ballast for the breaker point ignition systems instead of using a big ugly ceramic ballast resistor. It will drag your HEI power supply down to about 9V instead of 12V. I encourage you to take a voltage reading on that power terminal with the engine running to confirm.

You definately need to get rid of that and replace it with a new copper wire to a IGN source. This has been covered in the archives, but I'll summarize a couple ways of changing it. The best way IMHO is to get a new Packard terminal and replace the terminal at the firewall bulkhead connector. The second best way is to cut the resistance wire about 2" short of the bulkhead connector and butt-splice a new copper wire to it. The short piece of resistance wire won't appreciably affect your voltage. But that butt-splice will need to be clean and solid. I recommend packing it with dielectric grease and covering it with heat shrink tubing. Whatever you do, don't try to solder a new wire onto the old brass terminal. It will eventually leave you stranded on the road.

As for chokes, I personally run my choke and HEI off the same power source. Some people are concerned about the load it places on the ignition power supply. IMHO, that's more of an issue with breaker point ignitions. Although, if I was trying to squeeze every 1/10th of a second out of the car, I'd go for a separate IGN power source for the choke.

Well I tore apart the wiring harness and removed the terminal from the bulkhead connector, I removed the old wiring completely, cleaned up and sanded the terminal clean, crimped in a new 14 gauge wire, soldered it well, heat shrinked it and installed the terminal back into the connector! No more resistance wire!!
Not sure why you mention not to solder to the terminal, I made sure I had a good solid crimp first and then soldered for the best possible connection, that connection isn't coming loose or going to fail from what I can tell!
At the HEI I crimped and soldered the 14 gauge into the new terminal connector Procomp provided as well as a smaller 16 gauge wire that then runs to the choke. everything is soldered and heat shrinked, then wrapped in new friction tape!
Side Note: Found Friction Tape at the local grocery store where nick nacks are sold like extension cords, work gloves, etc.

Not sure why you mention not to solder to the terminal, I made sure I had a good solid crimp first and then soldered for the best possible connection, that connection isn't coming loose or going to fail from what I can tell!The OE wire is nickel plated and solder does not stick to the plating. You will get a cold solder joint, hence as dnult suggests, leaves you on the side of the road.

The only way to "join" another wire, regardless of material, to nickel plateing is to braze it together with a miniature torch and fluxed brazing rod, or crimp it then add shrink wrap with adhesive glue inside. This way as you heat shrink the tubing about the connection, the glue becomes soft and flows into the strands of the wire and the rest of the length of tubing. Then, the glue hardens up as the glue cools to form a watertight connection.

Good to know, luckily I scuffed up the connector before crimping and soldering, thus I was able to flow solder into the wiring and bare metal that was exposed. I did not see any difference after scuffing with sand paper so its also possible in 1963 that no nickel plating was used on this connection or that the plating had completely oxidized off. Previous connection was just crimped on, wire to terminal crimp, new connection is now crimped and soldered. 1963 Chevy II Nova

It's difficult, if not impossible to get lead/tin solder to stick to brass. The solder might flow well enough to appear solid, but I doubt it's adhearing like a good solder joint should. Vibration, a little moisture and the resulting oxidation will eventually separate the solder from the terminal.

Well these terminals/connections weren't brass, so I guess back in 63 they didn't use brass yet for the firewall connections.

I dunno, I do em the way Brian did all the time, they never come loose. It is important to clean / sand the terminal, and to have a good mechanical connection before soldering, but it sounds like Brian's got it done right.

Isn't a 12 gauge wire required for HEI?

Well these terminals/connections weren't brass, so I guess back in 63 they didn't use brass yet for the firewall connections.

Ahh, that very well may be the difference. My 68 is the earliest model year I've done the HEI conversion on. 71 Nova are brass also. So I just ass-u-me-d ;) You should be fine. If you start noticing a miss or no-start / no-spark condition, give the connection another look.

MSD Manual says 14 gauge is sufficient