At 69, I agree that tall bars make things easier on old backs. The TL250 is a heavy beast. I had one and it weighed 250 lbs without gas. It was also a bit short of ground clearance compared to other bikes. It did have a very nice fork.
I find that the TY175 is the easiest bike to ride by far. It is maybe 60 or 70 pounds lighter than a TL250, not a whole lot more than a 4rt. It kicks easy, starts easy and turns very tight. Power is slow and very easy to control yet it easily lifts the front wheel to go over things. For a mid 70s 175, It is quite surprising what kind of hills it will go up in 3rd gear. It is not as capable as a modern bike but easier to ride because you are not constantly working the clutch and brakes. Even with modern shocks, its primarly weakness is suspension. When going up a rocky creek bed like they seem to do all of the time in the UK, you feel like a ball in a pin ball machine. But, that may be true of most twin shocks. If you don't do a lot of that, you may really like one.
If you are set on a 4 stroke, a Honda Reflex is also much easier to ride than a TL250.