There really aren't any adjustments to compensate for wear. The steering box has two adjustments, but they are really for manufacturing tolerances. Assuming they were set properly to begin with, trying to use them to compensate for wear is very likely to result in binding under some circumstances. I recently ignored my own advice, and now the steering doesn't want to return to center as it should (plus I still have almost as much play as before).
So my suggestion is to live with it, until you are ready to start replacing the worn parts.
It's worth noting, perhaps, that the TR3 steering system is designed to have some play when off-center. If the steering box is not centered to the front wheels, you can wind up having that off-center play when the wheels are in the straight-ahead position. Most alignment shops seem to not understand this concept.
There is (or was) an aftermarket piece intended to eliminate this "off center" play, but I don't recommend it. My experience has been that it usually won't solve the problem, but will make the steering much harder.
Causes of excess play include (roughly in order):
1) Broken/missing rubber in the "silentblocs" (the joints between the center link and the pitman/idler arms).
2) Wear in idler arm.
3) Wear in tie rod ends.
4) Wear inside steering box.
All are relatively inexpensive to replace, although rebuilding the steering box does take a few special tools & techniques (plus having the box out of the car). TRF sells some aftermarket replacements for the silentblocs that should last much longer (using Delrin instead of rubber).