I used the 5 key set to key-alike a HF 26" box, 2 side boxes, and a 5-drawer cart. As far as I know, they only offer a 5-key set, otherwise you end up with individual locks which defeats the purpose. There were some modifications needed. The key set was designed for the 44" box system, so even though you're putting it on an older version, there shouldn't be too much fussing needed. It will depend on whether they changed the connection to the drawer locks or not.
See my write up on the 26" box to see what you might be getting into. The part number for the set is somewhere in the thread. The link is in my signature. I'd go for it.