There are basically two styles of brackets out there. Up through '68. Chevrolet used a short water pump, which used one style of bracket/pulley combination. In '69, they started using the long style water pump which had its own set of brackets/pulleys. You can use the long style brackets on your car if you aren't worried about which style you use, but the long brackets move the alternator to the passenger side of the engine, whereas the short brackets have the alternator on the drivers side. This will require a little rewiring of the wiring harness if you go with the long style, but it's no big deal to do that.
Experience...... It's what you get when you didn't get what you wanted.
well the reason i was asking is because there is a guy on craigslist selling a set from a 70 malibu. My alternator is on the p side and i have a long water pump. There is also a couple other guys that are selling brackets but all they list is big block ps brackets