Originally Posted by thoroco
I've used this one without modifying anything and keeping the original pedals both brake and clutch

http://www.performanceonline.com/1947-55-CHEVY-GMC-TRUCK-POWER-BRAKE-BOOSTER-KIT/

I believe its the same as master power's unit
That kit will not fit without modifications.

that kit will require at least one modification on a 1950 3100, (The O.P.'s question)
the transmission cross member will have to be modified or relocated.