[86GT]

I did the swap in my 86. I noticed a considerable gain in horsepower, but I also made some other mods that may have made that too. I'm still relatively new to carb tuning, and that makes tuning a Demon really interesting. Don't let anyone tell you that a carb'd car can't be tuned for fuel economy, power, and driveability. They were after all, on every car until the mid-80's.

Igntion, go with a stock distributor from an 85GT (5-speed). It'll have vacuum advance, and a steel gear. Use an MSD, Crane, some good aftermarket box for ignition. Coil is your choice, I matched my MSD6AL with a Blaster coil, works nicely, with my MSD Distributor (POS but it works).

What are you going to run for a fuel pump and line? I'd suggest the Aeromotive street rod pump (way better than the Holley ones), regulator, and 3/8" or 1/2" line. You'll have to make your own pickup or sumped tank tho.

If you go with a 570-670 Street Avenger you'll find good performance and economy, but I'd suggest a 650 double pumper Holley. That'll really work well with an Air Gap (same one I'm running) intake. You'd still have some good bottom end, but 3,000 and up, it'll take off. As for cam, well I'm not sure what to advise you on. Assuming stock heads, there's not too much advantage over a stock cam (which you can advance/retard) for more power. With exhaust, gears, etc. Air Gap, 650 DP, stock cam moved 4* (not sure advance or retard, someone please chime in), you'll be happy with the results.

Hope all that helps.