hi chris,
there are no boosters that will align with the existing master-cyl 4-bolt
pattern. you'll have to remove the firewall plate, grind the master-face
edges flat [where the bend 90deg for rigidity along the edges, and redrill the
holes- i never actually used the a-body booster- i prefer the 65-68 flat mount
c-body booster. and when using that, the firewall must be fully flush, for a
proper installation, which includes welding in a new section of firewall and
brake support bracketry modifications. perhaps someone out there actually
offers retrofits by now [?????]
i always do the conversions a little different each time, depending on the
application/drivetrain, available assemblys in my personal stock, etc..
the c-body setup has just become my fav after parting about 12-15 65-68 low-mi
full sized mopars with nice useable parts. the master of choice is the
74-78 D100 master when converting to discs whether it be power or manual. still
readily available with the perfect fluid proportions when used with the
aspen/volare discs and 7/8 rear cyl later rears.
also- keep in mind the the leverage ratio of the current pedal assy is
inappropriate for the power booster- there is too much of a mechanical advantage
at the moment, and chances are the pushrod for the booster will not work
favorably with the factory hung pedal. i always used the entire assy,
including the newer pedal, you have to mate the new and old assemblies together
[by cutting, welding, and adding a gusset plate] so that you have the intergral
strength from the firewall to the steering column/dash mounting point.
i'm figuring the a-body booster was chosen for clearance... but usually the
booster will end up higher than the original centerline of the orig master
anyway. the standard [older] c-body booster will work with original
drivetrains as well as tall deck big blocks, exc hemi or sonoram intakes in 57-9
cpdd's
jim