Welcome to the Forum and I hope you get your Cub real soon
I now have 3 of these little beauties, and I can tell you that they can do an awful lot of work. For 10 hp they can out plow, out haul, out mow any ot those so-called GT series overgrown and overpriced lawn mowers. I have a Craftsman 12.5 hp lawn tractor and it is not 1/20 the tractor my Cubs are.
Also the HP is not rated the same and is similar to comparing apples and mangoes. The B&S or Tecumseh engines are rated at developed HP with NO load and the Cub's 10 hp is measured at the drawbar with a load. Check out the Nebraska Tests results, which will indicate just how much work a Cub can do. Remember, these tractors were designed for 40 acre or less farms whose primary crops would be tobacco, corn, cotton and of course the usual truck garden variety of crops as well as potato's.
They were also designed to last only 7 years. Now almost 60 years later they are still running strong. How many ride on mowers would last 60 years
Probably not one
So for your 3 acre field, the Cub is ideally suited and it wouldn't even break a sweat doing anything you want it to do on your property. You do have to keep in mind though, the Cub is not a 4 wheel drive 80 hp tractor and it does have it's limitations. However, so far I have not come across too many so far. I have 25 acres of mixed wood lot, gardens and meadows/lawns and the only thing that has stopped me was a 40 foot maple that proved to heavy for my Cub to yard to the road