Oil and Temp guage

[77ChevySharkBite]

Hey guys,

I just have a few couple questions on my truck I haven't really worried about it, as my truck has seem to run fine, and still is.

It's a SBC 305 with headers and true dual exhaust, my question is my temp gauge isn't even working, and I was going to put new gauges but changed my mind and I had taken a few gauges out. One was my oil PSI gauge, well now that's reading when the truck is off at 60 and when I turn it on and it starts to warm up it'll go read up to 120 which I know for a fact is a misread because it was working fine until I had pulled the gauges.

My question is how can I trace to check if my temp gauge works, and same for my oil pressure gauge? Thanks for all the help in advance fellas you guys rock and are always so helpful.