Even in average condition it is well worth it. Clean, pristine, vintage touring bikes like the 520 can bring about $350 around here. So one in so-so condition, that needs some work, would still be worth $150, probably more than that.

Now if the question is whether it is the "right bike" for you, I probably would give a totally different answer. Does it fit, what do you plan to do with it, do you like/want a vintage bike? etc....

It might not be the bike for you at all.