sounds like a great idea. just a word or warning you might want to start planning on how you are going to use the space before building so you'll be ready when you are finished. Reason being even though that is a good size space almost any size isn't big enough. ask the guys with 40 x 120 if they wish they had a bigger or another shop or storage.
I'd love to have my own 40 x 40 barn, shop or garage, but i'll have to wait until my bride retires so we can move out of the city.
one thing you might do with all your posts if you are able to is post a lot of pictures either of the barn (or plans or pics of similar ones), scenery or some piece of equipment you are asking questions about. some guys like to start a lot of threads or i prefer to ask questions or give input on a few where I've been happy with the guys talking on it or that i know a little more than the average guy about the subject so i can help.
welcome to the forum