if you haven't read it there is a lot of good info on this swap here:http://importnut.net/300zxbrakeswap.htm
it says "definitive" but there is quite a bit of info still missing, most notably the bias of the different BMCs out there as well as information on how the ABS computer handles the information, but in terms of just figuring out what all the parts are that you need and general install info it's great.
From my understanding the rear 300zx calipers aren't really needed and it's EXPENSIVE to add them because you have to convert the whole e-brake system.
the K's Silvia in Japan had 4-pison calipers up front (identical to the Z32 fronts) which is why the swap works so well, the rears are the same as the USDM 240sx rears.
While I'd like to get them powercoated I've half debated spending the money on a media-blaster instead and then just going with some brush-on brake paint. having my own blaster would be quite useful for combating rust too
though I'm not sure if brakes are a good place to dip my feet in it for the first time
technically I could just install them now as is since I've got brand new Brembo rotors and a set of stainless conversion lines (and my S14's an SE so it's got big enough wheels for it) but I'd rather pretty them up first