Depends... if your more concerned about air fuel ratios, overboost protection, and improved drivability a progressive is the way.
For a simple system whereas the car sees lower 20's for boost, then a SAC works great. Simple turnon and pump speed control. Same pumps on my stuff as the DIY kits.., the added expense is electronics.
As far as the use with race gas question, dunno. Probably wouldnt hurt in small quantities for reduced charge air temps. The reason for alky typically is to get away from race gas. Properly designed kit should get you the same results as race gas, typically, especially on a mild motor like yours. How fast on alky.. many have run in the 11's or low-mid 7's 1/8 mile. Boost, timing, tuning will determine this stuff.
Any questions..post them, or call. I'll do my best to help you.
Julio