Essentially, Naptha and lighter fluid are the same thing. I don't know that it really matters whether you use actual naptha or lighter fluid to clean unfinished guitars. It shouldn't matter what brand of lighter fluid you use either. The main thing that you are looking for in any kind of cleaning agent is something that will evaporate quickly, remove oil, and not leave residue. Both naptha and ordinary lighter fluid serve all of these purposes.
Personally, I would stay away from acetone cleaners altogether. I know they were suggested, but they can cause all kinds of problems with finish and celluloid binding. In theory, you can't hurt the finish of your guitar if you are using acetone to clean it before it is finished. However, the cleaner could cause finish problems if the wood is not dried properly before finishing. This is kind of a long shot, but there is no reason to chance it. I would just use naptha or lighter fluid.