I use 5.0 grains of Unique behind a 115 grain cast SWC, so that should be good for a 90 grain bullet also. I shoot this load in an older S&W .32-20, a Winchester Model 1892, and a Marlin Model 1894, with good results.

I will also be shooting it in an S&W Model 16-4, that I had Hamilton Bowen make an auxiliary .32-20 cylinder for.