I did mine last month:
http://www.rockauto.com 1992 300zx Twin Turbo fully loaded (aluminum 30mm), get rotors for the same ,most expensive you can find ($50 each or the like). They will sell you remanufactured.Only do this if you have a 5lug conversion already.Get a 300zx master cylinder too (get that from Ebay, and make sure its a 300zx MC for a 240sx)of course you will need steel braded lines 300zx style (enjukuracing.com or ebay), and a rotor for the rear can come from a 5lug S14.. plugs right in with no changes to the rear break calipers.
---This break setup is by far the best thing ive done to the car since the SR swap But dammit all that is friggin expensive$$$ $$$