First off, Welcome to OCC!
Second, I moved this thread to the proper section. The 123 is a IH built Cub.
Third:
I'd do a very loooooong list of things before I try to start any machine that has been sitting who knows how long, that I know nothing about. I wouldn't suggest just throwing a battery in and cranking on it. I'd check everything out first, and drain ALL the fluids and change the hydro filter before I tried starting it. Hell.... I'd pull the head while I had the motor out cleaning the mouse nest out of the blower housing. I'd be shocked beyond belief if it didn't have one after sitting in a barn for years.