The 44 Magnum is my favorite, most reloaded round. I have reloaded everything from a 123 gr. balls to 310 gr. "ingots", cast, jacketed and PCed. For starters I'd suggest a 240 gr. jacketed bullet with a starting load of the "mid burn range" powders for the Magnum; Unique, Universal, Blue Dot, etc. Leave the "full magnum" powders aside for now as you can easily reach your 900 fps goal with starting (safe and easy) loads of medium powders. There's always time to practice "Magnumitis" once you get the hang of the big 44.
Using 44 Special rounds in Magnum chambers is no big deal, just clean your gun when you get home and you won't have any trouble with the dreaded carbon ring. My very first shooting with my 629 was with factory Specials (what a let down!) and there was no ring in my cylinders to speak of. I have since reloaded mild to wild using loads right out on my manual's 44 Special section in 44 Magnum brass up to max. loads with magnum data with WC820, W296, and AA9 under 240-310 gr cast bullets (ouch!). My favorite bullet, which works quite well in my 5, 44 Magnums is Ranch Dog's cast RNFP. Accurate in my 3 revolvers and 10" Contender, and feeds well in my Puma