runing out of idea´s on what to improve

I will say on the carb I really like your basic Holley 750 DP. We had the 850 DP with a SP Holley Street Dominator intake on the boys car and ran 11.59 @ 116.97 . He switched to the Performer RPM and the 750 DP last time out and ran 11.55 @ 116.23 . So the 406 seems to like the 750 just as well as the 850 but I will say the 750 with the RPM had a better 1/8 time also as it was better on the low end. The 850 and Holley SD intake actually had more mph but less et. Just some info in case it may help you. Ron