Nice looking bike. Araya was a rim maker, and that name may be stamped on the rims. The Shimano 600 components look like they are from the 1978ish-1980ish era, when a Japanese bike would have had 27 inch rims, not 700c rims.

The frame on a Shimano 600 bike made in Japan would typically have been high quality Japanese tubing, consistent with the high grade components. Other than one or two models imported by Schwinn, I don't recall seeing Reynolds tubes on any Japanese bike of that period.

I suspect you will have to wait until you actually have the bike in your hands to see what's what. E-Bay ads seldom are known for accuracy.

Bikes of that era are good deals, if they are kept as original as possible. When folks "up date" 80ish bikes by converting them from five or six cog drivetrains to eight or nine cog drivetrains, they often spend a lot of money, and do not really end up with a better riding bike. If this were my bike, I'd clean it up, tune it up, put new tires on it, and enjoy it just as it is.