Originally Posted by RobbieTunes

Welcome to the forum and glad to have a Centurion owner, even if part-time.

Headbadge places it late 70's to early 80's
Lug lining means little, but Lemans models had that.
I'm guessing a Lemans 12 or Super 12, but I'm not sure.
Very similar bike to my '83 Lemans RS, but I'd put it earlier.

Serial No. - N0N5730
Hubs (Front and Rear) - Maillard, France 82 - likely not OEM.
Crank Arms - SR Japan, 80, In line with an earlier LeMans or Super 12...
Sun Tour Shifters and Derailers - Cyclone puts it 1979-80 from what I've seen on the Semi Pro's, etc.
Front Fork - CR-MO Tange Fork Blade (all chrome) - likely not OEM, but could be. I've never all chrome on a Centurion
Tires - 27x1-3/8 - 27's came as late as '83 or '84 on some models.