Power discs with manual trans in an AD

[Old Crow]

So, I'm looking for a front power disc kit for the '54 3100 I'm building for a customer.
The owner desires to keep the stock 235 and 4 speed trans, but wants power disc brakes.
So far all the kits I've found(Brother's, Master Power Brakes, CPP)say they won't work with manual transmission trucks, but none of the suppliers can tell me what the problem is. I suspect there's a conflict with the clutch pedal or linkage, but the truck isn't far enough along to test this.
Anyone out there tried to put a power booster on an AD truck while keeping the stock trans? If so, what did you have to go through to make it work, and which booster kit did you use?