Quick brake Question

[fastlane]

Heres a >link< to what a guy is selling in my neck of the woods.

I am using gmcpauls disc brake conversion on my truck with 9" power booster, will this work? LMC probably says its only for 71-72 because of the disc brakes right?

Also I noticed that the line going to the rear is 1/4" and reduces to 3/16 at the tee. well my old rubber hose was 1/4" on one end and 3/16" on the other the tee was all 3/16". The question is... my new stainless flex line is 3/16" both ends should I run new 3/16" line from the front to the rear or get an adaptor for the flex line?

Thanks for any advice.