A much better version of the 1979 catalog with specs is here--download the US version of the 79 catalog:
http://www.velobase.com/Resource_Too...alogScans.aspx
The specs look right, and so do the graphics and the color. That decal style apparently didn't move down the food chain for several more years--my 1979 Super Mirage was completely different graphically. It's hard to tell because the handlebars could be in the way, but it also seems that maybe the TC didn't have any head badge that year. According to the catalog, the 79 TC also came with a 6-speed Cyclo Pan freewheel, so the 126 spacing would be correct, although the bike now has a newer 7-speed replacement freewheel.
Based on this catalog, I'm going to tentatively conclude that I have a 1979 model containing some parts that had been in inventory since 1977.