There is a spreadsheet over on the Castboolit site in the Lead and Alloys forum you can download. It is an Excell based one that works great for figuring out the amounts needed to come up with a certain blend.
It works in pounds so you will also need something to convert ounces to pounds if your adding small amounts of tin to sweeten things up.
Hard to give just a blanket recipe since different pressures need different alloy. Don't get carried away with getting things overly hard though. I am shooting an alloy which only runs around a 12 BHN upwards of 1600+ FPS out of my 41 and my 454, with no ill effects. Just make sure your size is proper and you use a good lube. Personally I like the lubes that White Label sells and have had nothing but great service from them. They are family oriented so if they don't just jump right on and shoot you a reply don't get upset, they will get with you to answer questions and process your order.
Hope that helps.