Airtronic's newer servos with the "Z" connector will work fine. They've got blue connectors. The older-style black connectors won't work without rewiring.

The JR receiver won't work with the Tower radio. That radio is basically an old Futaba rebadged, and works on the negative shift of the frequency. Airtronics and JR are positive shift.

Unless you know the maker of the crystal, it's all trial and error. Is it worth your airplane and the safety of your children to save a couple bucks?