I have a suspect 'Hitachi' unit, the readings where a mix of exactly what you recorded for your genuine Z32's and one which was more in line with the fake Z32's, abiet with a slightly larger margin of variation. My multimeter batteries were juuust hanging in there so I wouldn't bank on the readings though.
I think I'll pass on it tho (until I have better information) and just wear the ridiculous price for a verified unit... (Or make the leap to MAP and modern ecu, as the plenum, cooler, piping is being changed anyway. Yet I still can't bring myself to pay the asking price for a Bosh Z32 hahaa.)