All this nonsense over a slightly different roof line and why didn't you just paint your 2+2 blue....?
Seriously, enjoy the 2+2 as it is, for now. Don't be in a rush to get a 2 seater the right time and car will come up. Right now your not earning that much money (just being honest) and I'm sure in a few years you'll have a better paying job and more cash to play with. I remember being on a low wage and wanting to do so many things and just not being able to do it.
I understand this sickness, but you should just chill out a bit. Enjoy the fruits of your labor (the 260z) and drive it around whilst keeping it in good running order. Save any additional cash you have so you can buy the right car when it comes up (or go on that overseas travel adventure with your mates) and then buy the car outright (no loans...) and then take your time to sell the 260z 2+2.
You'll get the cash back for the 2+2 and stick it in the bank and earn some interest on it. Or blow it all on an unreliable triple carb blow through turbo set up from the 80's Wangan Midnight Comics. Your choice...really..but the 2+2 shape is still attractive and it's still essentially the same car, plus as mentioned they do handle a bit better -> I never spun my 260z 2+2 180 degrees in the wet going onto a freeway on ramp (done that in the 240z though and sh%t myself - it was wet out).
Also you still need to save some money for a proper haircut - first things first.