If you put them in the correct place the 729's should work on all inputs.
The correct place is directly behind the volume pot. The pair of 324's behind the selector knob can be removed if you don't use any recording equipment, since they are the tape output buffers and drain power for no good reason if you don't have a recorder.
In theory all 32.5 line inputs should sound exactly the same, but in practice they don't and the ones physically nearest the front of the selector switch bar sound slightly better. On that basis you should connect the CD5X to the tuner input unless the first or second TT input has been converted to line level - in which case that might be better.