Henry named the Edsel car after his son.
Tullio named the Valentino derailleurs after his son.
The Valentino front was basically a reincarnation of the original pushrod Gran Sport, which works fine for half-step gearing (e.g., either my 49-46 or the original 52-48 on my Capo Sieger), but not much else.
I second the vote to try a 750-length Weinmann caliper in front.
You can tell whether you have straight or butted 531 from you seatpost diameter, which will be either 26.4 or 27.2mm, respectively, for a standard 28.6mm seat tube.
__________________
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069