One of the finest "back it up" powders there is . . . IMR 4756.
A Hornady 525 drops 32 to 32.3 grains in an 800 Plus (at least it has been with the 8 lb. jug I'm working on right now, of course the next jug could drop differently). I'm shooting for 33 grains (or just a hair more), I think a 534 will put me there better than a P/W T bushing. According to Wiz White's bushing chart showing the inner diameters, a T bushing is about .536 or .5365 as I recall.
P.S. Let me know if you have one you can part with SS.