welp polygon1
If you're buying new, and don't want to buy my 1980 Miyata OneThousand touring frameset (about a 56cm size-wize...), I'll point you to the Rivendell (aka RivBike) RoadUno.... if you can wait another 2 months or so... oy...
some info here: https://us7.campaign-archive.com/?u=...&id=a24d941b71

sizing, check out the Homer geometry: https://cdn.shopify.com/s/files/1/14...f?v=1706824082 (top row)

as for me, I'm going 58cm and purple.... but i can wait as i got too many bikes.
cheers!