[Deschodt]

I was gonna suggest a 912 also, but not really in hindsight: some nice 912s are out$$$ 911s lately, the cheap 912 chassis era is over, and if he's gonna "invest" 50-75K of his own money + a lot of time, IMO he might as well get more of a return on investment by doing a real VIN 911...
I would bet he can find a nice project T for 30-40K, something with needs, no problem. His top budget would likely buy a decent running/looking car to begin with so a project, no problem!
The Qs to ask is what does he want - LWB vs SWB... SWBs are more twitchy/fun/valuable/expensive/less powerful (staying stock), LWB are more plentiful, cheaper, more stable, bigger engines, and 72-73 even have a proper gearbox pattern ( I jest, dogleg people) - so there are choices there !

I would contact Adam at Unobtainium, and follow them on ebay, they pull out "projects" all the time (way below his budget) and I would stay away from BHCC and their documented legal troubles...