FYI: this is not my personal info, but on a may 3, 2002 tech forum for a black 65 GTO the guy related the facts of his conversion:
all used spindles from 84/85 2wd s-10 blazer, then all new everthing else. *important:
only mod needed is the lower ball joint or control arm needs to be shaved to fit. they used
www.globalwest.com for the parts. they got mast cyl from 75 nova and stock 65 gto power booster.
i won't pass judgement, but the guy did it for $330 in part costs vs 900-1000 via a new kit.
do with this as you may. steve