I installed a new 9" single diaphragm booster when reassembling the interior and brake pedal assembly of our '69 Mach 1. The booster was from CJ Pony Parts, listed as a direct fit for 69/70. I had to modify the rod to accept the brake switch, which I thought was odd at first. Now I'm to a point where I tried to install a Wilwood master cylinder, and the rod length is totally off. I measured vs the old booster (Bendix dual 8") and the old booster rod is 0.25" longer and almost 2x the diameter. I cannot extend the new booster rod enough to hit the 0.020" gap. I thought about machining a new rod extension but this thing is skinny and I don't like it being unsupported for 1.2".
Wilwood included an aluminum spacer (PN 300-13885) for short rod boosters or direct manual brakes. However, this spacer fills the entire MC piston cavity, making it too long. Is there any reason I can't drill the spacer out to accept the [new 9"] skinny booster rod? I'd be boring about 0.25" in, which will also support the rod better.
Anything I might be missing? I had brakes completely fail one time (not due to incorrect install) in 2009 and I have been paranoid ever since.
