"Will the 6EX be able to link with non spread spectrum Futabas?"
You are reffering to buddy box, YES it will with the right trainer cord.
I dissagree with a previous recommendation of APC prop for that setup for training purposes.
I would use a Master Airscrew 11X6 prop. It can take more abuse than the APC. It is less efficient but that is something you don't have to worry about with your combo.
http://www3.towerhobbies.com/cgi-bin...&I=LXZ971&P=ML