MY opinion would be on appreciation on the uniqueness of the car alone not based on value , for example there are many convert their gtt to rb26 and claim gtr and some with only bodypart and claim it as gtr, first u need to think about time and money spend to convert this and that and must be prepared for extra expenses if anything goes wrong while doing this,and worst end up ur car value decrease because u have converted engine or changed bodykit.On the other hand some really appreciate and prefer original stock care without modification as to reliability and the stock look.btw did u check out the car?im not sure is it different tone colour or carbon fibre or carbon kevlar bodykits even if any of those it is abomb outside to purchase separately. End of it ur money ur decision bro!