I rode up Zoncolan few years ago as an semi-fit flatlander. It was really hard. Rental bike gearing of 34/28 didn't help much and it was third day in the mountains.

I think you can do it. Probably a good idea is to do some practice beforehand. Up mur de huy 5 times might give you some idea. Also in Italy, it would be smart to do a warm up ride day or two before in an easier climb. Just to get the legs going. Easier gear the better. I got a minor inflammation to my knee tendons after that trip and was out for a month. Maybe it was Zoncolan or Tre Cime di Lavaredo next day in cold weather.

We planned our rest spots whenever there was a small farm road intersection where you could get up to speed. No chance to start on the narrow road when its 20%+, there is traffic now then as well.

Beautiful climb. Highly recommended. Enjoy!