Hi Lar
Questions before proceeding the original CMP brake booster as used on C60 series has a special linkage which is necessary to make it function.
There are several threads on MLU on the topic which I will try and find and post links. Here is one
http://www.mapleleafup.net/forums/sh...ter#post220149
Having said that the booster makes the brakes on both my C60S & C60L have good brakes with out the booster these trucks with a full load would not be safe to drive over 25-30 MPH the stopping distance would be to great above that speed.
Last time I serviced one of my boosters decided to measure the boost at 15 inches of vacuum the mechanical force exerted by the booster was around 325 LBS. Now to figure additional force on the master cylinder you would need to work through all the math of the linkage pivot arms in the linkage.
Cheers Phil