The widow of a friend of a friend gave me some of her late husband's reloading stuff. A couple thousand cast bullets, 220 grain, .430 diameter. A 4-lb. can of Green Dot, and a 4-lb. can of Herco.

Can't find much data.

Does anyone have a recipe that will get around 1150-1200 fps from my 7 1/2 inch Super Blackhawk?

Herco, I loaded up some once. Very dirty shot 220gr lead fp shot good.
11.5 to 13.5max for a 220gr bullet.. had some stuck cases as I go up to 15grs cylinder was very dirty

try 9.5-10.0 grs of the herco.
it's step slower than unique.

green-dot is a step faster than unique and a step slower than red-dot.

I agree with Lamar, 9½ to 10 grains should be a sweet spot with Herco.