308's were a factory option in 5-speed Fox's. My '90 had them as well.
12's with 150-shot!?!'
Yes, 12's w/ a 150 shot assuming the OP is new to drag racing and isn't going to get much better anytime soon when only getting 2 runs in on a 5 hour window. Also when adding NOS for the first time you need to learn how and when to use it. You can have a fast car but it's only as fast as the driver.
Heck when i was new to drag racing I'd be a little nervous/excited and had so much adrenaline going through me that my legs would start shaking just a little bit and it messed me up. Took me several races before I calmed down a little bit but i'd still get butterflies from time to time.