Since it is a regular Blackhawk it will handle up to the medium heavier loads. Some reloading manuals have 3 different loadings for 45 Colt. The lower (original factory type loadings) for Colts SAA and clones and the New Vaquero's. Then the medium which Blackhawks, Bisley Blackhawk and the like can handle. Then the heavy magnum loads for the 5 shot specialty revolvers (Linbaugh, Freedom Arms etc).
I have a Blackhawk and they are excellent revolvers and are bult very strong. They will be fine with any reloading within reason however, if you want to make a 460 S&W out of it you might be better off to buy a 460 S&W or you might have an issue or two. Proceed at your own risk.
I have a Blackhawk in 45 Colt as well, it's a beast! I shoot fairly hot loads in it and no worse for the wear. It's often part of my deer hunting combo.