Have you explored Backyardmetalcasting.com (now alloyavenue.com IIRC) a wide range of alloys were used in Biblical times often depending on what the intended use was; (mirrors use different alloys than swords for instance.) a 90% copper 10% tin was a common alloy---I get my tin from rotometals.com)
May I respectfully point out that due to liability laws in the USA; you are basically asking us to risk our house, car, shop, savings on whether you can follow directions correctly and will take the proper safety precautions. Unfortunately I'm not willing to make that bet based on what I have read.
I learned taking an out of hours metal casting class from a local university's art department and have been using my forge to cast silver, copper, brass, bronze since the early 1980's. (Mainly blade fittings...)