This just posted in S. Philadelphia...though the link seems to be through Baltimore. Don't think the frame size is 50", but a hell of a lot of bicycle for $350 bucks!
If I wasn't 500 miles away, I'd at least go "kick the tires".
Harry Havnoonian Road Bike - $350 (S. Philadelphia)
https://baltimore.craigslist.org/bik/d/philadelphia-harry-havnoonian-road-bike/7453805738.html
Vintage Harry Havnoonian Road Bike for sale. Good condition. See pics for information. Saddle bag with spare tubes tools included. Text me with questions or if interested
bicycle frame material:
other/unknown
bicycle type:
road
frame size:
50 cm
wheel size:
28 in