Well, I'm not expert but I'd say go for fit and then comfort above all us. Gearing will come into play also according to the route.
It's a little newer then what you are considering but I took a 1989 Lemond Ventoux and turned it into a comfortable century machine for me. The key for me was the contact points. Went with a Brooks saddle that has always worked well for me. Then since most roads out here are rough chipseal I addressed that. This is the only bike I put bar gel pads under the cork tape on. It winds up thick but my hands never get tired on it and it really kills all the road imperfections. Then the other reason I picked this frame was decent tire clearance. It the past I ran it with a light set of November wheels with GP4000s II 700 x 28 tires with latex tubes. Last year I swapped them in favor of some tubular rims with veloflex vlaanderen tubulars for a really cushy ride. Years ago I had tested my fast C.F. bikes against several steel ones and found out that for 100 mile rides the extra compliance and comfort of the steel frames let me ride the distance faster as my body just wasn't getting beat up. Hence this build and my foray into mainly all steel rides. For me also I wanted the pump peg and two water bottle mounts that were low enough on the frame to carry the larger camelbak bottles I prefer.
The 700 x 28 setup
The tubular setup