Stuart, I have 60 year old eyes and also shoot a T/C (Renegade) with the T/C 1 in 66" barrel. A couple of things worth mentioning... My Renegade simply won't group well until it digests at least 100 gr. of Goex FFg behind a .490 RB with .015 or .020 patches, lubed with either Hoppe's No. 9 Plus, or BB. It loves heaver charges, unlike my other Renegade with the 1 in 48" barrel. As for sights, I use the T/C Hunter Peep mounted on the tang, and a T/C fiber optic front sight. You mentioned that you do not use the screw in aperture, but use just the "ghost ring". I found that just using the ghost ring does not give me enough of a distinct outline. Using the aperture only works in very bright daylight....SO... I removed the aperture and drilled it out, using the largest drill that would fit the inside of the tube (the tube that screws in the sight, looking from the front), so I now have the largest hole possible while still using the screw in aperture. This gives me a big enough hole for dim light conditions (and the fiber optic front sight really shines here, no pun intended). And, using the drilled out screw in aperture gives me a very bold outline to center my eye in. Short of going to a scope, this is the best setup for me. As mentioned previously, a barrel mounted peep is much less effective than a tang mounted peep.
Hope you find something that works for you...
Larry