Hello !
I do not know from where you'll buy the film, but it must be near film making industry ?
Why don't you ask if you can borrow a darkroom a couple of hours and ask them if you can re-spool the 400 ft into 4 100 ft spools ? They probably have a winding device just for doing that and will be more experienced than you in handling 400 ft of film in one single piece. find boxes and masking tape to put the 100 ft pieces into, have a bulk loader at hand to check what amount of film it can exactly handle, be gentle and friendly and prepared to pay a beer or two. That may do the trick...