You definitely have head room on the temps there... temps are a bit high for 2.5 GHz, but they can handle a bit more heat than that
If you get your hands on a P45 you should be able to clock the crap outta that chip.
I am a n00b clocker but managed to push my q9300 up to about 535 FSB on air. back when they were new.
( I do not even recall what heatsink I had, but it was in a case kind like that one... hmm irony for you... the case I sold to my boss with a ASUS p5 something board, and it just came back for some janitorial work recently...)