As previously said here, the temp sender has one wire. The EPS has two - 12 volts and ground.
Again, unless you have a dual diaphragm vacuum advance on the distributor the EPS SWITCH is unused. Most like me who have the dual diaphragm distributors just disconnect it. So what is the EPS wired to and why ?
Smart and easy money is on the sender. Buy a new one then install it where it belongs ( in the block ) and see what you get. Just assure the ground - sender to the block is good and that the block to frame is good. There should be a ground strap of engine to frame. If still inop then it's probably the gauge provided there is voltage at the sender. If still inop then send both sender and gauge out for bench testing. Keep in mind that a lot of parts being sold these days like temp senders are Chineese junk. So an out of box failure is not uncommon. That will drive you crazy if you let it.
Good hunting.