Actually, several people have dont the conversion.
They did have to fab up the mounting bracket for the calipers.
Their was one club member who built a very nice red Vega.
He not only installed the rear disc brakes, but a Corvette steering column, also.
Hd had a very nice web site with complete step-by-step details and color photos of both projects.
This back in the early 2000s when H-Body was on yahoo and then V8Monza.
Does anyone remember the guy and/or the web site.
In the meantime, try this site for some helpfull info.http://dave.h-body.org/H-body%20Conversion%20Tips.htm
John (John and Richard)