Are these temps while in motion at highway speeds, in traffic, or standing still ?
Fan shroud ? Send pics please.
Do you have access to an IR temp gun ? We need the temps at the upper hose and also the lower hose after the engine warms up to 160-180.
Remember, the rad filler MUST BE HIGHER than the highest part of the engine where coolant circulates. If it is below, then you can get an air pocket that will drive you crazy.
What octane gas you running ?