I don't know that much about how long the Diana 34s were made so its unlikely this one would have a leather piston seal. BUT... if it has a three ball sear, taking it apart will cause a bunch of little springs to come a-flying out in all the wrong directions.
In all reality you could probably shoot it without harm or you could send it to Ed K for a basic tune. I don't have the website handy but he'll make sure your rifle is set up the way it should be. Generally it seems that not just Diana but most airgun manufacturers don't put much lube in their rifles from the factory if at all.
That's a find of a lifetime if you ask me. Good for you
Harv