I don't see a superstar getting in the NT at a big man slot in any nation other than micronations. PF will have too low TSP (SF same problem, plus he's too tall) and C will cap much earlier than other players with better potential. U21, yes of course but you'd want to be around 60 right now but one year younger. For the NT he will also compete against all sorts of lower potential players with high initial TSP count.
Your best bet is as I said: train the guy to an efficient 120-ish TSP. 'Point forward' should work as long as you are not too picky about his OD and make sure you control JS punt his SB (keeps salary low and cap space open). This is kind of a best case for that player in my eyes:
https://i.imgur.com/m6eiWpg.png (with a choice of 48 skills in IS-ID-RB, 17-17-14 or 17-16-15 etc.). It's a nice player, but from a foreign nation I don't know if it's worth the investment.