Thanks to everyone for their help.
I took it to the game warden this morning. He verified there was no legible serial number, I signed an affidavit about where I got it and how long I had it, paid the fees ($80), and voila - title, Texas issued hull number, and registration number.
Based on a '73 with a sail number in the 7000 range, and a '76 in the 18000 range, I said I thought it was a '75. Well, now it is, by act of Texas! (at least that is what the new title says).
Now I can concentrate on refinishing it, and getting it ready to sail (3-4 weeks I guestimate).
Thanks again for all the input.