I've got the classics and the temp's work accurately. I took classic's oil sender and put it in the oil filter relocator which screws to the block. The coolant sensor of course replaces the mustang coolant sender.
I'd start the car, have it warm up and wait for the thermostat to open. When it does (you'll feel the hose to the rad heat up quick, the temp should come down about 10 degrees (for a minute or so) as the cold water starts circulating from the rad, into the engine. If you're pegged, the thermo opens, and the gauge still does not come down, I'd say they sent you the wrong sender. Of course if the temp gauge is reading correctly and you're really getting that hot, you might warp your block
If you know someone with an infra red temp gun, that would be perfect. Run the engine, and see and hit a few spots around the sender and on the Al tube you put going to the radiator. The temp should be close to what your gauge is reading.
For the oil, kinda the same thing. Regardless though, the oil sender after driving a while should get to at least 160-170 regardless of the thermostat you're using.
Good luck and keep up informed.