hey TheRockGuy,
you can check how close your player is to his cap range using either the USA offsite tools, (log into bb-usa.net), or buzzer-manager.com. For both you'll need to set up the Access key for your team (under Preferences)
Allstar potential can get to pretty high OD, but it really depends on his other skills (especially passing and handling if he is listed as a PG, JS/JR if he's a SG; rebounding counts a lot for all positions). So it's impossible for us to tell without knowing his skills.