Temperature Guage Issues

[my67c20]

After installing the motor and using the original wiring harness i kept the temp sending unit in the drivers side head, not wanting to fully trust that i also installed a temp guage in the passenger head. While running the factory guage reads hot and the temp guage reads about 180. My questions is does the factory guage have issues? Is there an issue reading the temp from the passenger head since these heads are interchangeable? This is a new sending unit. I do have a shroud that is about 75% coverage, the bottom section is missing. This appears sitting and driving. My coolant overflow tank is empty and my coolant level never changes. I have no apparent overheating issues. This is a 383 with a manual trans. Any thought appreciated. Thanks