i know it's kinda ghetto...but i had the same problem on my old KA-T setup. i ended up making a gasket out of 2 soda cans (traced the flange, and cut the cans, then over-layed the two pieces...basically had a 2 piece gasket). i later went back and got a piece of sheet metal and made the gasket from it (.125 gauge). the coke can gasket leaked A TINY BIT, but the sheet metal worked out just fine.

you should be able to get a small stock of sheet metal from a building supply company (like GRAINGER), or if you know someone at a body shop or even an aircraft mechanic (where i got mine). good luck

EDIT: i just thought about it...DIESEL INJECTION might sell the proper size gaskets to fit. bring them the turbo or just give them the info off of the data plate.

diesel injection
231 Main St
Forest Park, GA 30297
(770) 361-2222