Technical Fiat 131 twin cam inlet manifold query

[Birdyboy]

Hi, new to Fiats, just bought a 1976 124 Spider with a replacement 2.0 twin cam engine. Unfortunately got water leaking problems with the inlet manifold. Looks like the single carb and manifold setup was retained from the old 1800 USA smog engine. Is the old manifold and 2.0 TOHC head compatible? If so, will the carb take much setting up or should I ditch them both and go straight for the twin carb option? Any pointers will be much appreciated.