Welcome to the affliction, 458winshooter! I had casting equipment for a couple of years before finally falling off the deep end several months ago.
I like it so much I've even cast boolits in the 100 degree heat we had several weeks back. REALLY looking forward to some cooler weather.
I'm thinking some tin and antimony will harden up your alloy and make it useable, lead-free solder seems to have the correct proportions. My Lyman moulds were designed to drop a boolit of nominal weight using Lyman's #2 allloy, suspect Lee's were as well. There are some charts around here and elsewhere showing alloys and corresponding hardness #'s so it's just a matter of a little math and you'll be able to adjust your alloy to something more useful.
My next Midway order will likely have a .535" round ball mould. I have a .54 Hawken around here somewhere that's developing an appetite for recycled stick-on WW's.