4th gen LS brakes on a 2nd gen with 9"

[70PTRS]

I have a complete 4th gen LS rear brake assembly that I'm going to install on my 70 Camaro. I'm ordering a narrowed 9" from Quick Performance tomorrow and will be sending them the backing plates/dust covers to install for me on the rear. I'm also presently installing a complete DSE mini tub kit with 2" drop leaf springs. Has anyone else done something similar and if so do you have any tips or advise for this rear brake swap? I've read where some have had to use shims behind the backing plates to center the calipers over the rotors.
I'm also planning to use the complete parking brake setup from the 4th gen including the console and parking brake lever.