Even though some people say "Why bother, an old K6-2 450 and MB and RAm is only $30 off ebay" I think overclocking old CPUs is ace.
I got my old 100 to do 133 without any errors, it wouldn't push 150 or 166, and those were the only jumper settings available.(Bar 120)
Not many early socket7 motherboards have features that allowed overclocking. I didn't need to increase the CPU voltage though.
If you want to upgrade the CPU, 150mhz may be a limiting speed as the MMX chips need two voltage supplies, I can't remember the exact standard, but see if you can find out more about the motherboard.
A bios upgrade might give more options for overclocking, if you can find one.
Joni