Stew Wilkins is worth a try. had some 71A parts (mainly bearings and seals) ordered from them a few months ago and the service and pricing is excellent. Also just found a set of NOS synchros in the Netherlands but will need them for myself unfortunately
Not sure how z-related these are, Checkman gauges: https://www.ebay.com/itm/JDM-CHECKMAN-WATER-TEMP-GAUGES-METER-240Z-260Z-280Z-510-SSS-1200-SRL311-DATSUN-/162061515738