Having had both sized early zolatone marins either would work for you. I’m 5ft 9 and actually prefer the smaller size. More top tube clearance. The pic below was of my team Marin which was the same size and the seat tube was set up for the correct height.
Testing the water to see if anybody is selling a pair of these? Need to be in the dark grey with black chain rings as per the pic. Looking for decent condition.
I’d look for a 19/20 inch as I’m 5ft 9.5 with fairly short legs and I opt for size 18 inch. Kona frames have a sloping top tube and a fairly long seat tube length above the top tube (if that makes sense).
I built this 18 inch a couple of years ago and it just felt a bit too big. As you know they are over 20 inches centre to top. Good luck with the build.
Do you recall what Scott size frame this was? 17 or 18inch perhaps? I understand that they measure from centre to centre. I am looking at an 18 inch 91 Scott frame at the moment and just wondered how it would compare.