I referred to some of this in a post above. I estimate that I will have at least $200K in my car when it is finished- and the definition of "finished" is a moving target. "Finished" to me means that the car runs and drives, can be taken out and driven on a trip or the track, and come reasonably close to the performance and experience one would have had in a similar car back in the day. By that criteria, my Kirkham is finished. It seems reasonable to have the same expectations here. That does not include 100% originality or a show-quality paint job, although the level of fiberglass work and finishing in the Annapolis area is very good indeed, because there are so many boatyards here that do FRP and paint work. I expect that the car will look very good indeed, but not Brazilian bikini-wax good.

Well maybe close. No body fat on a GT40, anyway.
If you want to attempt this, the key things to remember are the following:
-GT40s are inherently far more complex cars than Cobras. Not that the systems are that much more complex (although all the remote plumbing etc makes a difference), but the basic structure of everything is a lot more tricky than a Cobra. This complicates EVERYTHING.
-if you buy a roller and then put in your engine and transaxle and get it going, you will STILL have plenty of work to do and will definitely feel as if the car is yours, no question. This route was not available to me. SPF wasn't around, CAV wasn't around- the only people around were ERA. I think they make a nice car, but the presence of Chevrolet Corvette parts in the build was a discouraging factor for me. I don't think Fords, even copies of Fords, ought to have Chevy parts in them. (full disclosure, 1149 has a Weber clutch disc that is actually a Ch--y part number, because of the transaxle splines. Muy tragico, senor) I had quite a bit of work to do getting the Kirkham going, and it is the best Cobra replica going. Good enough for CS, anyway, who is their biggest customer. For myself, if I were starting now, I'd buy an SPF car, maybe even their race model, and tailor to suit. As a matter of fact, if someone offered me a lot of money plus an SPF car for 1149, I might seriously entertain the idea.
-creating a vintage 1965 car from scratch is an idiotically difficult undertaking for a professional race shop. It is completely mad for a person like me who isn't even a trained mechanic to try to do it or supervise it. ("for God's sake, Jim, I'm only a doctor") I would not try this again. The amounts spent SO FAR would easily pay off my house mortgage and buy me some very nice cars in the bargain. Like the 365 Boxer I had to pass up, and others I don't want to even think about. Three or four of them could have been in the garage instead of 1149.
Upsides? I've met a lot of terrific people, I've learned a lot, I know a lot of things I didn't know, and when the car is done I will have created one more of a car which was a legend in its own time and is still al legend in ours. And some night, I hope, I'll drive across the Bay Bridge and head up US 301 and open it up, praying I don't get clocked on radar, and try to imagine what it must have been like to drive those wet and dark roads in midsummer in France in the 1960s, when these cars were in their glory and won the races they were designed to. For a middle-aged doctor, that is probably as good as it's going to get.