Pulled down a couple old manuals just to see what I could see and the only loads I see listed for 571 are for the 44 mag and 44 special. There are also some listings for 357 mag with light weight (121gr.) cast slugs. The original application for 571 is listed for "the very heaviest of 10 to 20ga. magnum shotshell loads".
Hodgdon Data Manual 24 has numerous listings for HS-7 in 357 and 44 but none for 45LC. When I get a chance later tonite I'll pull out some other manuals and see what I can find if no one else offers up anything.
Like Bill said, e-mail Phil at Hodgdon. I'm willing to bet he will be willing to offer up some assistence.