yeah good question here. I think basically, there isnt optimal strength for a 5'10. Probably just dont get too bulk up, be as strogn as you can be without losing your quickness.
And you might be referring to maybe upperbody strength, especially when it comes to shooting?
If so, I'm not so sure, but maybe as long as you can fade away jump shot from 30feet away without losing form, then you are srtong enough? just a guess.
chao