Your options are kind of limited because the only fans/air coolers you can get for am3+ from what iv seen that you dont have to do anything like add a support plate to the back of the mobo or what have you, are the standard clip style am2 am3 am3+ fans. now i can tell you any AND I mean any fan you replace the stock fan that came with your 6300 will be at least 30% better. I actually took "desperately" a fan from an old am2 dell I had that came stock with an asus fan "idk why" and I got a dramatic decrease in temps on my fx6300.
http://www.newegg.com/Product/Product.aspx?Item=9SIA4DR1F56945
anything like that would do you better but if you want better then that your going to have to do surgery.
With a similar fan to that oc.d to...