Aluminum block would be my most difficult but most effective weight reduction mod. It took off around 80 lbs from the front end. Here is my car's weight on autoxcuda's scale last year at Big Willow.

If you do the math it ends as a 55%/45% front/rear split.

This was with 295's still so my car will be a little heavier this year with 315's. Fiberglass bumpers, hood, trunk lower valance, steel bumpers brackets, gutted interior with no wiper motor. Lighter wheels are a toss up as you really want stiffer and wider wheels as possible. Wider tires also weigh more as well. I'm going to work on gutted doors as I have a mild steel cage