WOW! That was a boat and a half. I was a youngster when it came out. I've never seen it in the bucket seat, 4 on the floor configuration. Value on something like that would be hard to come up with. If were in great shape and ran good, here'* a page with comparable models
Search results for Pontiac Bonneville 1959-1969 in Cars & Trucks
Kelly drops value to salvage($500 under '86). Then you get into a unchartable territory of what ever a buyer will pay. Something like that with a frame off restoration and looking showroom could bring a price as high as $50k. But with alot of experience in and around Custom work, I can tell you that it can cost nearly that to bring a car that old to show condition again.