Actually you can use the 300ZX brakes in the altima, but the process is...definitely not for novices. Ask CM_David how to, he's done that plenty of times on the bluebird.
Edit: on a side note, since David doesn't really like to be bothered re-explaining what's been written, you can check teamNSE.com forum, under the suspension upgrade. I'm moderating there, but just don't feel up to it to post a link right now, as I've posted it as a follow up under David's thread as well in .net's general section. And I've actually posted a link in one of the old thread in this section as well.