I recently purchased an 85 Rx7 model S without a dead pedal.
If you know where I can find one, that would be great.

 

welcome to the forum. unfortunately this is the wrong place to post this. u will need to post a want to buy ad here:

https://www.rx7club.com/market/

 

The S model never came with a dead pedal. That was a standard feature on the GS and up. The mounting points are there for it and it is a simple bolt in part. Post a want to buy ad in the classifieds section. I'm sure you can come up with one that way.