If I was going to try to convert for a reasonable/budget cost, I would choose the
Motobecane Grand touring because of the bombproof, lightweight
Vitus tubing and my drivetrain choice would be
Suntour V GT Luxe hands down.....My wheel choice would be
Super Champion with
Normandy Luxe high flange or any good quality hub from Japan and my brakes would be
Vainqueur 999's. The GT feels semi-aggressive, speedy and responsive but not too much so.
I think that another great choice would be a mid-70's hand fillet brazed
Schwinn Superior again w/ Suntour V GT Luxe, because of the supreme blend of speed and comfort.
If I had a bit more $ to play with, I would probably choose Moto's The Jubilee made of Reynolds 531, which I believe had shorter rear stays and may be more appropriate for a Randoneur....
But honestly, I'd rather have a full-blown race bike and a full blown touring bike than a randoneur...I either want to go extremely fast, or I want to pack heavy, not a mix of the two