Not to throw a monkey wrench in the works here, but Uberti just introduced these Blackhawk-esque models in .44 Mag. Real world price should be around $500.
http://www.uberti.com/firearms/images/1873_cattleman_callahan_steel_lg.jpg
And, of course, all the other guns in the Cattleman series:
http://www.uberti.com/firearms/single_action_cattleman.php
And the Bisleys and Bird's heads:
http://www.uberti.com/firearms/stallion_bisley_and_cattleman_bird_head.php
The Rugers are good guns, I had an old model Vaquero .44. I've handled the new models, and they are more svelte. But IMO, the Uberti's just feel better, and have prettier finishes. They can handle the same kind of "+P" .45 Colt loads the new Vaquero can. Most of the Uberti's are also available in .44-40, which is pretty much your hot-ish .44 special and then some.
Here's Buffalo Bore's "heavy"
.44 Special.
Out of a handgun, .44-40 will get closer to your 1,200 FPS (safely) with 240's than the .44 spl. will. I did a little digging, and loads that get 1,150 with the .44 special exceed SAAMI maximum 15,000 PSI in a 7" test barrel. (Generated 15,400 per Hodgedon).
The listing of +P loads will get you there, but they are specifically denoted for large frame guns (Blackhawk Hunter, Redhawk, S&W N-frame, etc) The new model BH and new Vaquero are considered medium frame guns, though I'm sure the heavy topstrap on the NM BH can handle the "+P" stuff.
Just food for thought.