Should i buy new tires? 30 ys old?

im buying an 1980 kawasaki 44ltd for $650-700. 1st off is that a good deal? orginal owner 10,000 miles, nothing on the bike has ever been replaced besides oil changes..over good shape for 30 years. but my main question is, is it dangerous to got like 70mph on 30 year old tires?? the treads still good!