I've never seen a high flange Helicomatic. It usually has a big ol' HELICOMATIC sticker on the hub.

As far as whether it's suitable for touring... I'm a wuss and I would want at LEAST a 28 big cog in the back- yours looks like a 21 or so.

As far as the 620 and it's position... it was ALWAYS a good and upper level touring bike during it's time of existence- always second only to the 720.

As far as the 1983 Trek 620- it's only slightly less desirable as a touring bike because of the sidepulls (but even the best touring bikes of a few years prior had sidepulls and centerpulls).

As far as YOUR particular bike... It looks like you've had the wheels replaced- which I think is a good thing. Check to see what those hubs and rims are. If they're not stamped, the QRs might have come with the hubs. It looks like you've got a really nice derailleur upgrade with the Cyclone MII setup.

IMO, I'd get one of those 6 speed Shimano 14-28 freewheels (or the 14-34 if you're carrying a lot of weight). Steal the Sachs/Huret shifters off your Passage and replace whatever is on the 620. Then score a set of dual pivot Tektro brakes (I think they're the R539), make sure your stuff is greased up and go to town. IMO, dual pivot sidepulls have as much 'stopping power' as any of the canti brakes I've used.