This method was outdated so I am replacing it with a link to BlueHands website which has some updated information regarding the Volvo conversion.
Sadly his page points back to 311s.org
Also, Spriso Motorsports offers a 300ZX big brake conversion kit. Info can be found on his website. Contact him directly for information
As to the stock brakes they work just fine. The only recommendation I would make is to have the pots re-sleeved with stainless by Karp's Power Brake out of Upland California. Unless you change your brake fluid regularly the stock pots end up going bad eventually. The re-sleeved stainless will last a very long time. Last I heard Karp's was having issues getting the rubber rebuild kits but to me this makes more sense than buying new OEM pots every time they start leaking.