If he has 2 guys that are 7'0 and 6'5, then it is going to be hard to train all of them effectively. Sure he could train the shorter guy in OD or passing, but then is 7'0 guys will train very very slowly during those weeks.
I was thinking in terms of effectiveness, I think he would get a lot more for his team if he trained 3 7 foot guys that can all increase their skill quickly, and are focused on the inside skills + passing + Jump shot. Rounded players are more affordable, but considering he has 2 really tall guys, they are going to train very slowly in outside skills. If it is a question of affordability, he can always sell one of them before the end of the season for a nice profit and then buy a rookie and start the training process again.
If you are honestly telling me that you would opt for 3x 7ft guys, I either won't believe you or won't take any of your other replies across the forums with anything other than a pinch of salt.
Even if he does opt to train 3 x 7ft guys he wont likely be able to afford the salaries after 2 seasons... and considering its going to take 3-4 seasons to properly train anyone worthy of a return off the transfer market then I would argue there are much better ways to plan ahead.
The profit margins seem too small right now so at best lets assume he sells one trainee out of 3 (a 7ft guy) keeps another guy as his starting Centre then buys a new guard trainee(s) with the money and trains the 6'5 guy with the new trainee(s).
7ft guys also from my observation train slower in passing than shorter guys and training 3x 7ft guys at PG, PG & PG is going to severly dent your chances of winning 3 games in a gameweek... having the 6'5 guy gives you flexibility with regards to what you train and gives you the ability to maybe train Guard skills if you are definitely looking to throw a game.
So you keep trying to justify to yourself that the 3x 7ft guys is the way to go.... I am convinced this is not the route you would take and therefore am questionning why you are advising so.