Gtx 560m overclock

I've been looking for answers all around but there seems to be mixed feelings about overclocking a laptop's GPU. Some say to never overclock a laptop's GPU no matter what kind it is (gaming or not) and some say it's okay if it is within safe heat temperatures. So I just want to get to the core of it.

Currently, my laptop has an NVIDIA gtx 560m graphics card. In a room with an 85F ambient temperature, idle temperatures sit around at 45C on stock clocks. At 99% GPU load, my temperature rises to about 81C. When I overclock it, the temperature at full load is about 83C. Games I play in this 85F room make my overclocked GPU hit 75C.

However, generally, my ambient temperatures are around 66F because of my AC. The reason I am not putting up temperatures with a 66F ambient temperature is simply because I am not around a properly working AC at this time and won't be until I go back to school.

Small other small pieces of information are I did recently clean out the dust with a vacuum cleaner and I did not replace the stock thermal paste.

So, are the temperatures safe enough to justify the overclock, or should I seriously not overclock it. Thank you!