Engine runs hot

[newbraunie]

Installed mechanical temp gauge. Highest reading sitting on driveway - (can't drive truck since master cylinder cover off and along with other pb parts are off being plated....getting ready for pb conversion) is just under 210degrees. When I rev up engine it cools down to 190-195 degrees. I assume driving truck at 60 mph with more airflow through radiator it will run even cooler. I am playing around with the two (old and new) temp sending units. Have them tucked between lower rad & heater hose and alternating gauge comnnector between them (also grounded to battery) and they transmit identical readings although at low temp. I am relieved that engine is not overheating, OK with 190-195 degrees. I don't really want to install mechanical gauge as permanent so I may try another new sending unit with no thread sealant to rule that out. I also cannot find any wires grounding block to frame so I will take care of that. There is ground from valve cover to firewall and neg battery cable is bolted to cyl head. I am leaning towards conclusion that this is a grounding issue since replacing sending unit did not change gauge reading and old sending unit was installed with no thread sealant. Thanks to everyone for their tips and suggestions!