Are there any local Morgan Clubs in Texas/California/US? I guess that there must be. The Australian one was very helpful in helping me find out more about my car. They often keep a register of cars.
Morgan themselves will be able to tell you about the build spec and the like (see there website, for a small fee!); assuming you don't have this already.
Also the Morgan Register (click here
) may have something if a previous owner entered some data.
Happy hunting and enjoy the car!