disapoining et
Slicks first 26x10x15 on 15x8 wheels, you need to be hooking up to make tuning judgements. I'd replace the Performer with a Performer RPM, not an M1. Use premium fuel 91 oct. If cam wasn't degreed in during build, get it degreed in. Total timing at 38-40 degrees. You didn't mention exhaust system, but if its anything less than 2.5 its costing you power. I won't run less than 3" on anything performance intended. I doubt the suspension work would do anything for you at this point. Now if you put in a 4500 8" converter and 4.56 gears then suspension work would do something for you.
good luck