I am way late to this convo but I have to agree with a lot of what has been said already. I think taking a stock door and making it a COE door and then making all the necessary changes to the door opening, rockers, etc. would be Kindig fabricators territory. The inner door structure would have to all be hand fabricated and really would take experience to get all the door gaps and adjustments correct. On my cab, there was a little bit of rust where the front of the rocker connects to the cab, I believe when this was repaired by the well lubricated body man that helped me out, he did not get it right. I have never been happy with the door gaps on my truck.
Windshield-I rebuilt mine years ago including new glass, weather-stripping, the hand crank etc. I have never had a leak and it still operates great.
Cab size-ask Hambone about the size of my COE cab in a parade in Leonardtown MD ...in 95 degree summer heat....lets just say we had no choice but to bond that day.
As far as a replacement cab, my bet with some serious digging and searching, you can find one without too much difficulty. Would you consider selling the truck you have and starting fresh? There is a guy on you tube, Iron City Garage I think that is dragging old iron home form across the Midwest. He does not seem to have any trouble find trucks. There are still junk yards out west that have great old iron in them and I still see a '46 coe cab or even a complete truck on Ebay from time to time. If you are a purist, I think you would really end up fighting that cab to get it even close to original and even then, might not be happy with it. I don't know if I would classify myself as a purist but am still glad to this day that I restored my cabover close to stock, even it is speed handicapped.
I try not to be a "you should do this" kind of person and I know what it is like to have folks disagree with you plan but maybe at least explore a plan B in this case.
Good luck which ever way you end up going.
