Overclocking P3-500 --> P3-800

ovrclock it a step at a time until it wont run then try to up the voltage to get it to run stable
it is really a hit and miss on overclocking because two identicle systems can perform dramatically different when overclocked

i got a 550 doin 733 easily @133mhz bus stable and temp maxes at 46c
yesterday i upped the fsb to 148 and got 814 stable with default 1.65v (played q3 ran sandra sisoft etc)all this is being done with the standard hsf
im wondering what kind of heatsink (jus a air cooled one )shud i buy for the cpu
since at 814 my bios temp says 53c, AFRAID to go higher since im using standard hsf
here are my specs:
asus p3v4x mainboard
ati radeon 32mb sdr o/c 194/194 w/ coolmaster slotfan oooling
sb live mp3+
us robotics 56k pnp hardware modem
WinME
fujitsu 20gig hdd
4x4x24 lg burner
128 stick of 133mhz memory
p3 - 550