He played a left handed '65 Jaguar he found in a pawnshop that had been routed for humbuckers and the individual selector controls replaced (poorly) with a 3-way switch. He played mostly mustangs and Japanese Strats (some replaced with Fernades necks), with the occasional Epi or his Mosrites and Univoxes.
For a full list of his equipment:
www.kurtsequipment.com
EDIT: Nirvana was my favourite band when I was 14/15, and found Strat guitar with a JB through a Marshall will nail most Nirvana tones, a Tele on the bridge with the tone rolled back does well for Heart Shaped Box, and I find my Phat Cat Tele can mimic the tone of the Univox Hiflyer he used playing Heart Shaped Box on SNL. Your Jag HH should be able to cover a LOT of Nirvana ground, considering he used a HH Jag quite a lot.