Austin-Healeys are known for running hot. Usually, they'll hold set point (thermostat) temp when cruising--exceptions are pulling up a grade on a hot day and similar stressful conditions--but start to heat up when stuck in traffic. The 'cures' have been discussed at great length, but the best bang for the bucks come with a clean (hot tanked) block, uprated (clean) radiator core, an aftermarket fan (flex or 'Texas Cooler'), a fan shroud and extra baffling around the radiator. Side louvers probably help, though I've never had them (lack of airflow through the engine compartment has been cited as one of the heating causes).
My BJ8 will stay at or below 180deg most of the time. It has an uprated core, flex fan and shroud and the engine was hot-tanked at rebuild about 100K miles ago. Sitting at idle, or in slow-and-go traffic on a warm day the temp will rise to 200deg or more. At 65deg ambient and 50MPH, your temp should be 180 or less with a 180 thermostat; your engine will hardly be working in top O/D. If your car has the original core, the block has not been cleaned, and you have the stock fan that would explain your 190 temp. Also, check your timing--if it's retarded you'll get overheating, and running too lean will contribute (up to a point). The higher running temp won't hurt anything, until you get stuck in traffic on a warm day and you won't have as much margin before boiling.