you do not say exactly what car your needing the pedal and booster assembly for
?
I would look around ebay and see if anybody is offering a firewall mount ...UGLY , or an under floor mount assembly, kit.
The brake kit specialists offer the correct choices of ; small size double diaphragm booster, correct pedal ratio 7--1 , correct master cylinder for size and WEIGHT OF CAR , disc disc or disc drum proportioning valves, 2 or 10 pound residual check valves for under floor mount.
Just don't take something out of a car at the wreckers and transplant it into a street rod and hope it works, which a lot of times it will not. Do you really want to cut $$$$ cost on something major like brakes
You also need a motor that will produce 18--21 inches of vacuum at idle in order to operate that booster. Radical camshafts will only produce 12--15" of vacuum and car will not stop worth a damn. Stainless steel brakes corp makes a electric vacuum pump for this purpose
mike lynch