Ken was kind enough to send me some photos of his old ten-speed lightweight. Bought in 1976, and it looks like he took great care of it. The frame serial number suggests it was made in 1974, and maybe shipped from the factory later that year or even in 1975.
I would peg it as an SHS. The lugged frame has the shiny chrome-plated stays with Shimano forged dropouts, and a chrome-plated fork to match; with a sticker boasting of "Champion" butted cro-mo steel tubing. The head badge is the ubiquitous Sekine Cycle "Medialle", with a white fill. The seat tube has the CS crest topping Sekine Canada Ltd, with the modern SEKINE lettering on the down tube. It's worth noting the cable stops are Shimano bolt-on, as opposed to brazed-on.
The bicycle is equipped with the full Shimano package- Tourney centre-pull brakes, Fingertip downtube shifters, and Titlist front and rear derailleurs. SR double-ring alloy crank. Shimano safety-brake levers sit on a Sakae Custom "Road Champion" handlebar, held by an SR stem. Original chrome-plated seatpost and quilted seat.
The wheels have the common Shimano high-flange 'windowed' alloy hubs. The steel rims seem a bit out of place, as most models I have seen were equipped with alloy rims, though it is possible only later models had the lighter wheels. Ken had changed the tires, and added mudguards and a rear rack.
Ken admits is was tough letting go of the bike; hopefully whoever bought it treats it well.