Yes, if you're guns are handling 8gr Unique, BP will be fine. It's a different sort of power, for lack of a better explanation. Without a Chronograph, I'm unsure, but I think a case full of BP has more power than my 8.5gr Unique loads. More felt recoil anyway.
I started loading 45lc with homemade BP, 30 grains and a 250 grain RNFP lubed. Had to back it down to 27 grains of BP or so. 30gr was some serious recoil in the revolver. A heavy crimp allows the BP to burn up and pressurize properly.
You can't overload the 45 colt with BP, I think the max you can fit is around 40 grains GOEX. My max for homemade, since less dense is 30 grains, which is fine, that's a full case, lots of power, low fouling and highly accurate.
I prefer loading 45 with BP now over smokeless. There's no more mess than Unique makes, and cleanup with soapy water is easy.
I would suggest if you can, use GOEX express, or Swiss, you'll get better performance out of all you guns since the fouling is considerably less.