An '84 Lemans can be a lot of different levels. The RS was beautiful, black and silver, with Suntour components, piggy-back ratching shifters, Suzue hubs laced to Araya rims, very nice DC calipers/levers, Road Champion bars on an SR custom stem. Frame was Tange Infinity, I think. That doesn't sound like what you're seeing.

A Super 12, I'm guessing, would be earlier, and I have no idea what the component level would be.

Comparing it to an unknown Trek frame would be simply wasted time. I'd say the Infinity Lemans frame would be similar to a 510 or thereabouts, but not a 531-tubed 560 or higher.

If you're new to it, I agree with the others, get a bike complete. Learn on that, move up if you have to, minor investment for a lot of learning, fitness, and fun.