Brake problems

I run a booster that size on my Falcon. It does actually provide a fair amount of boost.

That said, there is no reason you should not run a much larger one.

 

just to compare what you have with what other F1 suppliers have try : hotrodstrucks.com - brake boost power 1948-1952 drum-drum & cl***ic-haulers.com - firewall mount brake booster kit. from what I have found 1 1/8" is common offering for drum-drum