I want to have a built performace short block ready to go. How long ( If everything went well) to swap out a motor?

I helped Clyde (socaldieseltech) swap a long block and it took around 3 and 1/2 hours. But Clyde can work on a duramax in his sleep. I've seen it!

It took me longer then 3 hours to switch stuff over from the old to the new motor, but I would say 2 fairly competent people should be able to do it in one day.;)