One manual says 9.0 grains gives 875 FPS and is a factory duplication load.
9.0 gr of Unique is hotter than any "standard" factory load I have ever shot, and 8.0 gr is just a wee bit hotter than most all standard "cowboy loads".
When I was loading for my 45 Blackhawks I used 9.0 a lot, they never had a problem with 250-255 grain bullets with this load. I no longer have any 45 Blackhawks and have only Colt replica's, so I can't go there anymore.
Unique picks up pressure pretty fast, half a grain is pretty noticable. Be careful working your way up to 9.0 and beyond, and remember jacketed bullets might have different pressure than cast bullets. I still use Unique a lot, always seems to be a good one to have around for 45.