All 5- and 6-speed rear clusters use a 5.5mm pitch, AFIK, and any Shimano 6-speed shifter, combined with a Shimano SIS derailleur will work. Hyperglide cogs will make shifting a bit less clunky, but are also more susceptible to ghost shifting. YMMV.

EDIT: when using a 5-speed cluster, you'll need the block the last click of the shifter with the RD limiting screw.