I'm having my front end and brakes done by a guy in Hurley, NY. I shopped for a looooong time for a disc brake conversion kit.
This NY guy, Rick, put together an all-inclusive kit for me for $630. The dust shields, proportioning valve, and spindles were used everything else was brand new. The calipers aren't stainless sleeved but he says it's rare to have a problem. The spindles are used but easy to wear-check. All other parts including ceramic pads, not cheap organic pads, are brand new.
Personally, I think you should give him a try. He's darn conscientious and his knowledge of repairs for FGF cars is extensive. If you want his e-mail address, let me know.
11" and 9"? I hear that the 9" is to make room for a Chevy Big block installation. I've only seen 11" boosters installed in FGFs.
After all my shopping around I realized that some kits are cheaper because STUFF IS MISSING. Read the fine print and you'll see that the booster is extra or the spindles aren't there.
I've had some guys tell me that the booster is unnecessary on a "light" car like ours. When I sell the car 10 years from now, I want to be able to say that it has power brakes.
If you don't go with Rick, buy your kit from Classic Industries. They seem to have the best kit at the best price. I allllmost bought from them before I found Rick. The C.I. price is $819. If you add just a few more dollars to your order, the shipping will be free. (I think.) The brake kit is not discount eligible (like the 15% you get when using their Visa card.)