I actually have 2 sets of "period" seats. The PO had apparently changed them to the later 4/4A type before it ended up in the barn. Needless to say, that they were horrible when it came out nearly 3 decades later; although the frames seem to have held up quite well. When I first got it back on the road I put a couple of cheap seat covers over them.
Last year I couldn't find any suitable Miata seats, so I bought a couple of similar vintage TR seats on eBay; passenger one 8/10, driver's 5/10. I had been using them up until now. I am a bit of a pack-rat, so I will keep the newer ones and probably the older ones (much to the wife's horror), unless I hear of someone looking for reasonable frames.
Aldwyn, it took me 2 days as I was modifying the design of the commonly shown adapter plates and then making them. I still have the original steering wheel and even with the period seats my right leg was not in the best of positions. The standard "Miata" mod makes this worse, so there was a lot of measure twice cut once happening. I managed to keep the seat height about the same, but I had to drill 2 new holes in the floor for the mount (it's a driver not a show car).
Russ, I didn't find the originals too uncomfortable, but the thought of a woman yakking on her cell phone while she rear-ends me (even at low speed) and leaves me and the wife with serious whiplash was not appealing. An inattentive driver rear-ended my Daughter last year and I seem to remember that you had your own similar experience, albeit from the side. As to the belts, I would prefer to minimize the chances of me eating the steering wheel in an accident. When I am on "the hurry up" around our local narrow twisty roads, my driving style can be conservatively described as "spirited"; I don't do ice-cream runs in it. Hhhmmm - maybe we need airbags in these cars?
Thanks for the comment on the paint, but it is still not where I want it to be. I have found that you get very picky when you do it yourself. Every car show I go to I am looking closely at paint, grading my effort against others. I should stop that before it becomes an obsession. I did get one comment where a guy complemented me on the color and I told him how I painted it. He then said that someone had approached him a few weeks ago and asked his opinion on the roller method and he had said that there was no way he should do that, even for just a driver. He then said, "If I hadn't seen yours with my own eyes I wouldn't have believed it". As I have said before, it's not for show cars, but for a "3-footer" it seems to work. I am currently experimenting with polishing methods to improve upon that.