As you may know Rotorheads a re fewer and further between than other types of motor/gear heads.
All I can tell you is what I have heard and that is that the machined parts in a rotary are "highly" machined and polished and very sensitive to being incorrectly abused.
You may find a simple bad seal in the rotor housing and that would solve the entire problem? Or it may be that something has been damaged beyond repair and you would have to replace it, or the entire motor anyway.
Hard to say w/o an up close and personal inspection... and being more knowledge about these engines.
Is the used/rebuilt turbo motor come witha warranty of some sort? Is it built to be stock, or has it been modded for additional boost/power?
Truth be told, I would probably have more questions than answer if I were in your shoes. I'd have to do some serious research to determine what the best path might be.

Sorry, but its the best I can do.

 

How much fluid did you find in the floor? The early 13b's usually leak oil around the intake injection oil pump on the lower right hand side of the front cover. This seal can be replaced without pulling the motor. How easy does the motor start? Does it leak more when the car is running? Just some ideas.

Steve