Thought I share this. This is quite a steal for a rebuilt engine. I'd be all over it if it was rew.
Mazda Rx7 13b engine and transmission

 

arn't those the 70's 13b housings?

 

83-85 beehive rear plate (Y casting). It has a T coolant fitting.
74-75 rotor housings.
Oil filter pedestal looks to be installed backwards (180 degrees out).

I assume the rotating assembly is from the 74-75 engine the rotor housings came from.

I assume all the side plates are Y castings from the 83-85 12A the rear plate came from.

All the parts together are probably worth the asking price. You might as well buy it.

 

Der frankenrotor!

 

Yea it sounds like one of your engines! :P

 

Dont look like no s5