On the brison and fpe engines around here we tend to see 7200 to 7500 with a 22x8 to 22x10 bolly prop.
I havent run a bambula prop but I would think you shoud see at least 6800 to 7000 rpm on a broke in 3.2.
What oil mixture are you running? How much fuel do you have through the engine? All of these things matter alot more on a gas engine than on a glow motor. The Brison will make alot more power after a couple gallons of gas.
Good luck with it and enjoy it as it is a great engine
Fred