You can get a Redhawk that shoots both now too.

I love the 45 Colt (and 454 Casull too).  I have 45 Colt Redhawks with the 5-inch and 7-inch barrels and the 7 with and without the rings.  I also have blackhawks and for heavy 45 Colt loads I really prefer the Bisley Grip as you were advised.  Of those I have guns in 5.5-inch, 7.5-inch, and a Bisley Hunter.  I find I shoot the Bisley Blackhawks best and they are more comfortable to shoot!  Either gun will handle massive 45 Colt power!

I will add I also have a Super Redhawk in 454 Casull and a Super Blackhawk 454 Casull as well.  Here, I still like the Bisley but when I hunt bear I like to hunt thick swamps.  If I ever had to mess with a bear at those distances and my normal 870 with 3-inch foster slugs was not in reach I always have my Super Redhawk just because it is so much faster to shoot if I needed to slam double action or reload.  For deer, I always carry my Bisley Super Blackhawk Hunter in 45 Colt!