Yes you can train whichever skill you want, mate. Normally people train 1v1 first because it boosts all other outside skills' speed and crucially trains IS as well (1v1 forwards).
At 6'9'' you should probably look to make him into a PF or SF (because height affects the training speed as well, so he won't train as fast as a 6'0'' player in outside skills like OD or JR, but he will train faster that the 6'0'' player in inside skills). In any case it really depends on the the target (the final build) you want to achieve.
Unfortunately if you really want to make a plan you will need to use one of the tools that were developed based on the evidence coming from the US offsite research. So either Coach Parrot or the Training Simulator.
Coach Parrot (Jozef Ka):
(119279.1)Training Simulator (by rhyminsimon):
(229484.1)Last edited by Lemonshine at 7/14/2017 4:41:35 PM