I can't give you a for sure answer. But.....the GM big cars began sharing a platform in 1971. So I'm gonna say yes. I suggest you have it looked up in a Hollander Exchange manual to be sure.
You can get new tanks on eBay. The Bonneville was a B-body, but is still a very large car. The capacity might not be the same.
thanks guy now for the big question. how hard is it to put a 455 buick in there. the pontiac was a dirt track car and is pretty stripped and i bought it to help clean up around my place ie pull trees oil drums trailers ect and not have to worry about damage