Low oil pressure on new engine solved

I had posted back a few months of 5lbs oil pressure on a new engine at idle and 20lbs at cold engine start up I bought a otc oil pressure test kit turns out my oil pressure at cold start is 55lbs then when motor is warmed up 20lbs at idle very happy my question is what is a good us made oil pressure gauge thanks in advance
Something used and old or something NOS. Sun, SW and even some of the cheaper parts store gauges back in the 80s were all made in USA.