I'm doing the same build, but as a no name car. I used the tubs from the AMT 66 Nova pro street kit, with little filling and they fit great, you can also slide the inside of the tubs into the frame rails, looks neat and is secure.
I used the Dana from the Revell 68 Charger kit, moved the springs in board as you did and also use the ladder bars. Looking at a video on You Tube, as the car was backing up you can clearly see the leaf springs on the big tire car. I used the slicks from a Polar Lights funny car with Future Attraction crowned super tricks. All most done, just glass and bumpers. Good luck with the build.