I'm into converting old school MTB's into touring/commuting bikes. There's no better base to start with IMO. Your bike is clearly pristene.

Having said that, I see that there is a steel, possibly cottered crankset on that bike, which leads me to conclude that it is a low-end Hi-Tensil frame. That would give me pause as to suitablilty for an extended trip. While there is nothing weak or poor quality in a well-built hi-ten frame, per se, you will pay a toll on the long daily ride in terms of the dead-like feeling. Everything will come thru the bike to you. In a week, you'll be dead-like, too.

Get on a bathroom scale and weigh it. If it's 31lbs or more, it's hi-ten. A good MTB frame will weigh around 28-30lbs. A high quality MTB will weigh in at about 27-29lbs. You can do things to lighten the bike, but you can't add much long-distance quality to a hi-ten frame.

It has good points: double eyelets, slender tapered fork instead of the baseball bats they used later, lots of fender room, long geometry, and a good size for road work. The single bottle position can be easily remedied.

If I'm right on my speculation, this bike would be a great street-bomber, but I'd hesitate to recommend it as a cross-continent candidate.

Your call...