Check out this deal on brakes.

[Jeff240sx]

No, don't buy 300zx lines. You will need special conversion lines (I only know of PDM-racing.com selling them, but others do too) and they convert from a banjo fitting to a flare fitting for the new calipers, while still hooking up to the 240sx. They are $90 or so.
It seems to be a decent price. Are you gonna need to buy the 300zx hardware kit? That will be shims and pins to hold the pads into the caliper. If not... I think you could get a better deal.
$200 for calipers (rebuilt), $140 for cross-drilled or slotted rotors, $90 for the conversion lines, $60 for pads, $55 for the hardware kit... and you're done. That comes out to $545 for your choice of stuff (rotors and pads).
-Jeff