As suggested above, we need to see a good drive side photo of your transmission to gauge what is feasible.
For example, I have found through experimentation that the Campag. Record on my Bianchi will not accommodate more than 26T. The good news is that stock gearing was 52-42 / 13-15-17-19-21-23, and going to a 42/26 bottom gear made a huge difference for me. Deferring to age, I now run a 38/26 low gear.
__________________
"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