Gaining

No way of knowing for sure because it depends on your metabolism and how it reacts to the change in your eating habits.
Doing it for one month is hardly enough time to have your metabolism react to the changes and actually change how it has been working all your life.
I think you are over thinking all of this with X number of carbs and X number of calories.
X number of calories does not equal Y number of pounds gained.
As much as some will say and try to prove it doesn't work that way in reality.
I ate like a pig for 6 months and only gained 10 lbs when I first started trying to gain.
My metabolism took forever to adjust to my eating.
Its different with all people so no cut and dried answer actually works.

I drank a quart of heavy cream in one sitting last night (over the course of maybe 30 minutes) and it left me feeling very full, sleepy, and interestingly, light-headed.

I started at half a quart per day and went straight to one quart per serving though. It took maybe 2 weeks for me to get used to how an 8oz serving would leave me feeling. But I did manage to gain 7 pounds in a month of drinking half a quart per day!