CARBURETTORS - KEIHIN FCR
The best carburetor ever made is generally agreed to be the Keihin FCR flat slide, and with the prevalence of fuel injection in recent years no-one is likely to make a better one. Unlike the RS36, there are not currently any off-the-shelf kits to fit Laverda. You can get a kit for Triumph triples in 39mm off the shelf which might make an excellent starting point for installation on a Laverda triple, though perhaps a bit large. The carbs are also available in 33, 35, 37 and 41mm.
500 and 750 owners will have many options for a starting point, there would be plenty of options from late model Ducatis etc.
One thing to watch out for with all carb conversions is the angle of downdraught - take care you stay within the manufacturers guidelines for that model, or else float bowl flooding can occur.