I've never upgraded the CPU on my 3000.

The ZIP ram was hard to source but was nice to run, the chip ram upgrade costs a fortune and ANY CPU upgrade for an amiga (3000/4000) is worth often twice the value of the machine. The stock CPU will run an OS fin unless you want to try and run that newer gimmick of an OS which to be honest assumes you spent around $1000 to max EVERYTHING out.