The problem is it takes just about as much money to restore a base model 4-door as it does the highline phaeton, and yet the value at the end is quadruple for the open car. It's a sobering formula.
If one did much of the work oneself, for a full restoration, you might come out okay, perhaps only losing $20,000 out of pocket on a resale, but your labor--which can amount to thousands of hours---would not be recouped.
Just having someone re-chrome and re-paint the car for you is a $10000 bill, if you want very nice work I mean. On the cheap, maybe 1/2 that.
I had a 29 Ford Model A 4-door town sedan which I purchased a bit shabby and running and I just did whatever was necessary to clean it up and make it safe. I had no desire to restore it and I was, in retrospect, very glad I didn't. People loved the originality and the patina of age that was all over it. Of course, it didn't have huge rust holes in it, and the stuffing and springs were not pouring out of the seats. But it had faded paint and chrome, a few tears and rips, and looked old underneath and in the engine bay. I drove that thing all over the place, even on 300 milers.