I'm not really familiar with the Fender Model T, so take anything I say with the appropriate amount of caution.
I agree with you that the 50/60 Hz designation implies that line frequency should not be an issue. I wouldn't worry about that.
Have you measured your line voltage? In your place, I would, just to make sure as to which would be preferable, 230 or 240. Other than that, as you say, it does look to be pretty straightforward.
When I lived in Italy, some thirty years ago, we used transformers to run all of our gear. The only thing that had any issue was my TEAC 4-track. The difference between 50 and 60 Hz made it run slow, so all of the recordings I made there are now sped up. Other than that, we had no problems at all, certainly none with any of our amps. I wouldn't hesitate to use it with a step-down transformer.