Mikesz, Yes I am still using an 83 N/A 5spd. The difference with my setup is I have an 83 N/A engine with a turbo added on. My compression ratio is higher and I have like no turbo lag when I accelerate. During hard acceleration I was in and out of first so quick it made that gear almost useless to me. Now with your turbo engine you will have some lag and what Pyro pointed out may be better for you.
You asked about a 3.54 with an n/a 5spd and that's what I ran for a few years and Liked it a lot in my car. I have a 3.70 lsd in the car now and like it a lot.
You said you wanted your turbo to spool up even quicker, but I was taught you want the turbo to be able to spool up longer. To get all the benefits from it, Not Quicker for a street car with a stock turbo. That's also if the turbo is stock.