My bad on the gauge - I hadn't realized you're in an 87. The gauges were different back then. I'm going to venture a guess that your cooling system internals are just fine, but you're right to be looking at the clutch and fan itself.
(man, an 87 2.9 with less than 100k miles on it? You must live right
next to the church you intended to drive it to on Sundays
An assist fan would be overkill, IMO, unless you've done some tuning or whatever to generate more heat within the engine (which I would consider just beginning to get broken in). So maybe if the fan blades are cracked, they're wobbling/flapping and not drawing the right amount of air. And if there's a problem with the clutch, they generally seize so that they're always engaged and turning, OVERcooling the engine, denying it the opportunity to get up to proper operating temp, but that's likely not the case here.
At this point, it's totally up to you how to approach the repair, and it'll get down to money; either keep it bone stock and replace what the factory put there, or "upgrade" to an electric fan. The E-fan might cost you more initially (I'm sure Flex-o-lite can fix you up with a kit; you may need an alternator upgrade), but you'll get it back over the years at the gas pump with slightly improved efficiency.
Another thing to mention is that there are additives for the cooling system that may help you keep the engine at a lower, steadier temperature, like when under load getting on a freeway, climbing hills or in stop-and-go traffic, taking some load off the cooling system itself.