Z2 RAM is bound to slow down the machine, so probably the smartest choice is a SIMM adapter and no-cost (or close to) SIMMs for it. If you're not planning to get an accelerator that is.
I am probably not understanding your advice, or, maybe I don't know what a SIMM adapter is. Doesn't the SIMM adapter go onto the motherboard where the Zip ram chips normally go? Isn't this location on the motherboard limited to 16 Megs? Aren't SIMM adapters themselves rare and still expensive?
ZorRAM goes for about $137. That's a little over a dollar per meg, not bad for a 20 year old machine.
EDIT: I think ZorRAM will perform best if there is some Fast Ram on the motherboard. It seems I read that somewhere.