The stock oil pressure sender is located on top of the engine just aft of the distributor. The aftermarket VDO sender is too big to fit in this location, so an "adaptor kit" is used. The kit is a piece of hose with the appropriate pipe thread fittings on both ends and a bracket that wraps around the sender. (The case of the sender must be grounded.) You screw the hose in (tough to do, poor access) and bolt the sender to a ground by its bracket. Mine is on the fan shroud.
The temp sender is in the front-left sump plate, the one that has two bolts holding it onto the bottom of the engine. There is a paper gasket and an O-ring as well as the crush washers for the bolts, and the rubber "boot" that goes around the wire. The sender has M14 threads, forget the pitch. I posted a couple of VDO part numbers to the 914 Rennlist
http://www.rennlist.org a while ago. Do a search of the archives for "sender" and you'll probably turn up the post with the numbers.
Good luck!
--DD