Probably quite a limited market for a 4 door Falcon, even with all the extra work..... Just because a mint restored car books for $6k, finding someone to actually spend that on one would be a difficult task. The restoration guys would deduct for all the departures from stock and the folks willing to part with big bucks for a Hot Rod are going to be looking at V-8 powered 2 doors.... I would say the only way you could get your money back out of the engine is to install it in a very clean and very nice 2 door Mustang, Falcon, Granda, Fairmont or similar..... The initial cost is always lower on the less desirable cars, but you lose the advantage on resale.... Kind of like the old Fram commercial, "You can pay me now, or you can pay me later." To tell you the truth, until the car is completely done, runs like a top and the body looks better then new you would be doing good to get back about 1/2 your investment. Right now, it all works good in theory......but that's it.....