It always pays to retain the "spool" anytime you get bulk film wound on one. The metal spools are sometimes called "eyemo" spools after the main camera that used them, or #10 spools which is how Kodak used to stamp them. If tying to buy some both of those terms may help in a web search.

The Legacy Pro film DID come on a 100ft spool which interestingly enough was Stamped "FUJI FILM"

In the Motion Picture world it is common for 100 ft loads to come on a spool, while 400 ft load typically come on a 2 inch core with a 1 inch hole in the middle. 1000ft loads may come on a 3 inch spool-again with a one inch hole. The One inch spools that Kodak and some other bulk film comes on are also handy to have as they fit the hole on the 2 inch Cores and allow the film to unwind freely without flopping around in the loader.

(TERMINOLOGY ALERT: A "spool" has solid sides while a reel has openings in the sides. hence 120 film comes on a 120 spool)

100ft 35mm Microfilm spools can be used if you can find a source of them they are almost identical to the movie film spools except they are often made of Plastic. The movie spools are generally of Metal to help keep Static down.

Some of the Smaller loaders will only have enough room for film wound on the 1 inch cores. I recall a data sheet that some of the Kodak Still Camera Colour bulk films were supplied on a 2 inch core at one time.