im not reading all that but, i had a 88 cs over 220k on it when i got rid of it, a 90 gp over 300k no abs i think my old mans lumi was a 91. none had abs and all i did was the rears had problems so if you get the parking brake working and use it, and the rear sliders working good i always got good pad life. my point is if it where my car i would just go get a regular master and booster from a junkyard and run new lines and be done with it.
1998 Bonneville SSE
2007 Monte Carlo LT-KYB, Clarion, Polk audio, Kicker
1999 Yukon SLE-KYB, Air lift, Reese dual-cam, Tekonsha
1987 Firebird-355/th400-nothing stock