I can add only a little to T-Mar's info. The 1984 Lemans RS had Tange Infinity tubing, the "piggy-back" Suntour shifters, DC brakeset, and Sugino crankset. It didn't have anything Shimano on it, as far as I know. As far as I know, no bronze-anodized components on that model; doesn't mean there weren't any.

There is an '84 catalog out there. The '84 Turbo carried a bronze-anodized DC brakeset and a bronze-anodized 52t chainring on a Sugino Aero Mighty crankset. I figure if your bike was an '84 Turbo, you'd be talking about the chrome under the paint, which it has. It also came in a dark red with silver head tube. The seat stay caps, dropouts, and R chain stay would be polished chrome. It was a 700c bike with Suzue bronze-hubs.

I can't speak to the frame, but I know the components a bit better. I can't tell you if it was Tange or not, unless you have a decal, or even Suntour, but at the very least, it sounds like a good bike with good components either OEM or upgraded. If there was a huge database of OEM frames and OEM components, I'm sure a cross-reference could get you close, if it was OEM. It sounds like a bike person owned it and maintained it for a while, but the mixing of 700c and 27" is odd.