Funny enough, I actually had one once.
I ended up getting a good deal for it, so I sold it and got a miata.
I have worked on FBs, FCs, and even and FD here and there.
Let me give you a little bit of advice. If you want to get an FB, get one of the last ones made with the 13B engine or get the 12 and be fully prepared to swap out the carb with a 4 barrel holly.
As soon as you buy a running RX7, go buy a second engine and get an engine crane. Sooner or later your apex seals will shit the bed and its easier to just swap the engine and rebuild the engine at your leisure.
Once you rebuild your engine with good atkins rotary and racing beat parts, it should last a good long time.
Also, forget about turbos. They complicate things, and quite frankly I like the power band of the NA engine.
Lastly, I would HIGHLY suggest you get an S4 FC and premix your fuel like your life depends on it. They are by far easier to work on, they have much better suspension geometry and they just feel better to drive. Its hard to explain. The FB is a little rickity, the FC is just super comfortable and inviting to drive, and the FD is too stiff and clinical.