Where in Texas are you?Big state-lotsa folks.Check with an Early Ford V-8 club in your area,also get Van Pelts book.Austin speed shop,Mercury Charlie and Rex Rod and ch***is are possible contact folks.
When I built my '36 3-window with a '50 Merc 25 years ago, I used a '39 case and later ('46-'48) gears. I did it all myself with an old Ford manual and a little transmission book from Speedway Motors. It was easy and turned out great. This is not a difficult task and you should consider doing it yourself. The experience is good to have. These days, Van Pelt Sales has all the parts you will probably need and they have a book especially for uses like this (and you can talk to Mac himself if you get in a bind). I found good looking, un-chipped used gears, and bought new bearings, thrust washers, and syncronizers. As I said it performed flawlessly, and while I broke a couple of axles in the 7 years I had it, the transmission was as good as the day I put it in when I sold the car. I think you will find that removing and re-installing the transmission a harder job than rebuilding it. (I hate torque tubes.)