What you may find is that the fasteners you get from these guys are not JIS, and will have larger heads for a given diameter bolt than stock. You may not care, but in a few locations they may not fit so well, and they will stand out visually.
I just posted about this in another thread, but I prefer to clean and then replate the original fasteners. I also went to a nearby junkyard last year, bought three BUCKETS of old Japanese fasteners from them for $25, spent one evening cleaning them, then spent $110 at my plater having them barrel plated. Finally I sorted them into a few bolt boxes I got from HF for $15 ea.
So for $200 and a couple of evenings' time invested I now I have a frankly enormous selection of new-looking JIS fasteners I dip into as needed, and it has been priceless at times.