which booster to swap from manual to power? need advice please

[68firebird]

well the bird is in the garage for the winter, so its time to start thinking of stuff I'd like to get accomplished over the winter. I'm thinking of switching to power brakes and I really want to make sure its done properly, what size booster would be best, 9 or 11 inch, does it matter? what else needs to be done for the switch, or is it as simple as installing the booster and hooking a vacuum hose to it? where should it be pulling vacuum from? thanks for the help and advice.

ps: please include any recommended parts, Links would be fantastic.