Turbo swap into an n/a FC is a large pain in the ass, just to let you know. Also there were definitely n/a RX-7s available in Japan. The FD was only sold as a turbo throughout the whole world but the SA (1st gen) and FC both came in n/a version in the Japanese market.

To get info check out:

http://www.rx7club.com/forum/
http://www.teamfc3s.org/forum/