A while back I bought a written off mk2 mx5, completely stock, repaired it & built it to a trackday weapon, suspension, brakes, rollcage, bushes, wheels, exhaust, supercharged, water-meth, harnesses the list goes on. Had 20k of fun in it, put it back to stock, sold the car & all the parts separately & turned a £400 profit. now that was some cheap motoring.
Unfortunately with the z33 there isn`t really a cheap way of going FI, there arn`t many boosted cars so in term picking up used FI parts is un common. So IMO unless your a real zed head or you have a real burning sensation in your pocket it`s not worth doing it to a 350z