I think F Bills right in that someone put a bushing in the head to adapt an electric sending unit. once you remove that bushing, you will need to install one of these bushings to accept the temp probe.
http://walcks4wd.com/temperature-gauge-bushing-at-h.html
   The mechanical oil pressure gage does not require a sending unit. Here's a link to a replacement gauge at Walcks.http://walcks4wd.com/oil-gauge-late-cj2a-cj3a-cj3b.html
This runs from the gauge thru the firewall.http://walcks4wd.com/oil-gauge-hard-line-mb-gpw-cj2.html
This runs fromte hardline to the block. http://walcks4wd.com/oil-flex-line-gauge.html
Matt

JB this is my running chassis using this wire diagram. Easy basic setup that is giving me all the info I need.

if you cannot get it to turn, take a grinder to the exposed surface of it and sand it down level with the block in two spots, to weaken it. This will also prove to you that it is a separate part...(wire brushing would do the same thing if there is any question of it being a bushing and not just a smaller hole in the head than normal ) Then take a dull chisel and hit it inward to collapse it on itself . You may need to chase the threads in the head with a tap when you are done, or you might get lucky and just need to use a wire brush on them.

An old school trick I have used in the past to keep shaving out of places is to use............Shaving cream.  Make sure you get the foam shaving cream and not the gel stuff.  Fill the hole up with shaving cream, get your bushing out, tap the threads, ream out the hole or whatever you need to do and then wipe out the shaving cream and metal bits it catches.

If the foam stats to collapse before you are done with the work, just wipe it out and spray more foam in.

Just a tip I picked up from an old engine builder a looong time ago.  I really didn't believe it until I tried it, but it works.  He used it a lot when he would replace a gasket on a V-8 and didn't want the gasket material to drop into the intake, block or cylinder (depending on which gasket he was replacing).