Dunno 'bout the size but you can guess from the pics below.
I guess 2x 172mm fans + shroud would be fine.
BTW, what is the best way to clean up those fins???? I gave the whole lot a bath for 15 hours in diluted vinagar and with a bit of Brasso, it's shines.
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P4 1.8a @ 2888MHz 1.85v CPU Load/Idle 55/36oC
256meg PC2100 (generic crap) 2.5-5-3-2 2.65v
Abit BE7 RAID (R.I.P BD7-II)
CPU:MEM 1:1 160MHz
Cheapo Coolmaster HSF
Full Atlantis system under construction