A member offers a free alloy calculator for download. Neatest thing since pull tab beer cans.
http://castboolits.gunloads.com/show...oy-calculators
This is an Excel spread sheet that will help you in two ways.
It lists many if not most common lead alloys such as wheel weights, different types of printers lead, solders, pewter, etc. This will tell you what you might use.
You enter pounds of each type of lead and at the bottom it lists what the mix will yield as an alloy and approx. BHN hardness the mix will have.