Agree you are running hotter than desired... not immediatly dangerous but not optimal. It sounds like the basic setup is very good and should keep you cool but running at 200 when cruising down the road suggests the radiator is borderline plugged - it should run cooler.

A good radiator shop can inspect and re-core your OE radiator if it needs it. That's where I'd start. There are all sorts of options but a good 3 core 26" should handle your setup fine.

Also, if you are worried about the guage spend $15 on another one and cross check. I never like to blame the guage when its easy to check.

Also it would be worth double checking the timing and distributor advance mechanism. If the initial timing advance is too low or the advance is stuck that could make it run hotter.