I spied a little clue in your post: "when sitting for a short time at idle, the temp guage will soar up to 200 F in no time"

Short Answer: Worthless stock radiator fan with no shroud really doesn't move air appreciably at idle.

Long Answer: There are two basic things the car needs to keep cool. First is coolant movement through the motor and radiator. The second is air movement through the radiator. The coolant movement through the motor is a more complicated issue, as there are multiple potential issues. But basically, if it is overheating at idle, it's almost ccertainly not a coolant flow issue. if that was compromised in some way (partically clogged radiator, partially clogged distribution tube, funky water pump, collapsed hose, dodgy thermostat, etc) then the primary symptom would be overheating under a load. When you are driving, the motor is putting out MUCH more heat, and without proper coolant flow the coolant bottled up in the motor will pretty quickly start to get hot. So if it overheats at idle, we can move on to the next issue: Air flow.

Volvo put a silly little egg beater fan on their old cars, with no shroud. I'm almost not sure why they bothered. If the motor is idling, the fan really doesn't do much in the way of moving air. If the motor is revved up, then most likely you are motoring along, and the air flow (well, vast majority of it) is provided by the air hitting the grille as the car moves along. Maybe if you are 'drafting' behind a big truck on the highway the fan is actually doing the work it was intended for, otherwise you could pretty much take it off an not miss it that much (slight exaggeration). Since practically no air is moving through the radiator at idle, it will overheat. My PV used to be able to sit idling and boil itself in about 5 - 6 minutes flat. Solutions? Install a better engine fan, like a flex blade like IPD used to sell. Or (even better, IMO) install a thermostatically controlled electric pusher fan in front of the radiator. That's what I finally did with my PV, it practically never kicks on unless I'm stuck in stop and go traffic on a warm day, or it sits and idles forever. Or after shutoff, it sometimes cycles on a couple of times which helps prevent boilover. And last but not least, just bump up your idle speed somewhat. The increased idle speed will spin the water pump and fan a bit faster, and they might actually be able to accomplish enough cooling to keep the motor cool.
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'63 PV544 rat rod, '93 Classic 245 + turbo