(Over)clocking - 350 MHz
The new K6-333 CPU has still some performance margins; this means overclocking it to 350 MHz should be successful with almost all 333 MHz CPUs, maybe with a 300 MHz type, as well. You should be familiar with the rules of overclocking from Tom's guides, thus I think it's not necessary to mention the risks and insecurities again. All others should wait for the official 350 MHz version which is to come still in fall 1998.
The Winstone differences between the two rivals were 5% at 250 MHz (the second official setting for the 266 MHz version), 4% at 300 MHz. The question was: Will the difference decrease to 3% or less? The answer may disappoint: The difference has grown to 7% due to the even faster L2 cache of the Pentium II 350 (175 MHz) and the 100 MHz memory.
Also incoming profits of the new features of all new 100 MHz Pentium II CPUs. The K6-2 at exactly the same clock speeds is 4% slower. Though the Pentium II couldn't outperform the K6-2 at 300 MHz, he will do this at higher clock speeds.
Quake II runs slower by 11% at 800x600 at 350 MHz. The Pentium II is clearly faster here.