There has been a pair of these seats on ebay for a few months now from Japan. They looked to be in fantastic shape. I think they were 545 each shipped. I almost bought them, then found a nice replacement for the drivers seat in my GTUs.

 

I have a pair in my car. They feel great for backroading and autocross/ track days. However they do sit you higher than the common fc seats. Being a 6'2, 135 pound guy I fit into the seat sung and comfy but with a helmet I do have to hunch over to fit into the seat. lol

 

I've seen these come up on Yahoo Japan a couple times a year. Shouldn't be impossible. I haven't seen a bride seat that fits an average North American or European for that matter. They may have newer styles that I haven't seen but, just my 2 cents.