The LeMans was Centurion's money-maker. Not their nicest bike, but a few steps above their bottom-end. Yours looks like early 80s, which means it's not *that* nice, but it should still be a solid rider and last for many years to come. The frame sticker is a good representation of this: hi-ten steel (low end) but butted (nicer than 90% of hi-ten frames out there).

Would make a good candidate for a fixed/single-speed conversion, if you ask me. Save some weight and the shifter clamp, cable stop and derailleur claw will come off for a clean look. You could convert to 700c at the same time and probably gain a bit of tire clearance, all the better for gravel rides.