For a saginaw pump you can get the March Brackets, they are about $100 or so. They work great and look good too. Another option for a sag pump is find a large ford or mercury with a 351m/400, like an LTD or something. The bracket will bolt up to the 351c but you will only use one of the head bolts, not both. I used this setup for years. Worked fine, just not as nice looking as the March brackets.
If you want a stock pump, just search ebay or junkyards for a stock bracket.