sell a full 531 frame in your size and kick yourself for all eternity.

love those olympic ribbons on the seat tube. they will open up several bar tape color combinations over time.

a donor bike with shimano 600 clamp-on stuff can be had for $250 or less. add a brooks, tires, and consumables, and you should be right at $500. and the bike will then look like a million.

if you need longer brakes, i'd suggest vintage long-reach center-pulls rather than new tektros, which often don't look quite right. if you do go the tektro route, you can often get a medium reach for the front that doesn't look so bulky. i did this on a couple 700c conversions on 531 frames. harris sells them individually.

i've seen a 65mm stem before, but that one looks tiny! like it's for t-rex arms.