I am not aware of many adjustable rear sights that fit the TC barrel hole pattern except some Williams sights, which I believe were used by TC as factory sights towards the end of their traditional gun production. If you are willing to cut a key way slot, a whole world of options are available.
I find elevation adjustment with traditional roundball gun sights not all that necessary, once you get your load worked out. I have a number of roundball guns that I have shot for over 40 years without adjusting the sights. When things change, powder for example, I vary the powder charge until I am back on the point of aim. I have notes for various powder manufacturers different granulations, and how much to load to get on target with the sights on specific guns, though group size may vary a bit.
With muzzleloaders shooting various conicals at varying distances, especially once you pass 100 yards or so, an easily adjustable and repeatable rear sight is about a must have.