Ok, fan - Pentium 100 or higher. Most P75 or higher had them, though 75s and 90s would do fine with an average sink, 100 with a decent sink.
Throw a contemporary heatsink on there and you might be able to run a 233 fanless or a very quiet fan anyway Socket 7 and Socket A use the same clips 🙂
Hey, you said it's for fun, get a big sink/quiet fan and make it look like one badass 233
(and enjoy the silence)
--Mc