60 ft trouble

I wrecked the 8 3/4 3.91 gear in my dart last year and replaced it with a 4.10 geared dana 60, I also moved the springs back 1 inch for drive shaft reasons, this car used to dead hook and do 1.39 60 foots with ss springs and a snubber on a 30x9 slick with a best of 10.12 @132 now with the dana I can feel the tires slipping and my 60 is 1.48 to 1.52 did moving the rear end back cause that much weight transfer problems or is the gear difference to much for the ss springs to handle? It has the same pinion angle, snubber clearance and shocks as before maybe its time to upgrade to the caltrac system? even with the crappy 60 ft the car went 10.13 @ 131 so if I can get it out of the hole I'm sure the car will like the new gear ratio. Any thoughts?