It's not out of the realm of possibility to find a rear hub like the front, a matching rim, and have it built up. That way you'd keep the original look. Once you go down the road of changing parts here and there(wheels, stem and bars, etc), it ceases to be a cool vintage bike. Just my humble opinion of course. Now if you had found a bare frame that had already been stripped, then all bets are off. Finding one that original however, is the proverbial "needle in the haystack". Are the bars just too low? If they're too low at the highest setting, then the bike is most likely too small for you. With that frame size, you'd have to be 6' 4" or better for that to be the case?,,,,BD