I have the same exact set-up on a 1969 Roadrunner. I put the spring purch in the front hole and drilled out the front hole on the caltrac lower bar holder/shock mount. I have the super stock spring hangers as well. Everything works great. I have a combo that has 525RWHP/500LBS TQ with a Richmond 5 speed and launch the car at 5500rpm. Wheels up and movin' out!