1,750 lbft, that's more torque than we were expecting...
The thing to do now is call the manufacturers of the transmissions you are interested in and see if they will stand behind it in your application.
I can't tell you what you need, I can only guess at the options. In the end it's your money and you need to be satisfied with the results.
What you are trying to do is a stretch for the capabilities of a manual transmission, it may not be easy or cheep to find a long lasting solution.
Grigg