I doubt that small a boost would do much good. The theoretical limit of Intel's older Klamath core PIIs is around 300-333mhz. Without any extra cooling, you should be able to reach 263mhz (3.5x75). And, if your motherboard supports it, you could make it to 290mhz (83.3x3.5) or 300mhz (75x4.0), but for that I would suggest better cooling.
As for the temp: I doubt you have excellent cooling, you either dont have hardware temp monitoring on your motherboard or you are using a program like CPU monitor and you didnt configure the voltages correctly.
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