Perk of a project bike is that you'll probably learn some good mechanical skills in the process. My last bike - and the reason I bought the FZ6 - was a 30 yr old CB750. It had, predictably, 30 year old issues.
After the third charging rotor that it melted (and a complete disassembly, reassembly, repainting (while replacing all rubber parts in the process)), I said **ck this and bought the FZ6. It had cooked a OEM charging rotor, an aftermarket rotor, and another upgraded aftermarket rotor the company made. 1980's NOS parts are too hard to find and expensive to mess with.
I guess where I'm going with this is - make sure the bike isn't too old and be prepared to becomes friends with the tattoo'ed girl at the Harbor Freight checkout line. If it's being sold as a project, someone already gave up on that project.... sorta like that 750 lawn ornament I have now.