Paul,
           While looking at used engines I am at a total loss of knowledge as to what actually wears out in a rotary and so what obviously it takes to overhaul a rotary to new condition.  In Oz it appears that any ":good" rotary is about $1500 to $2000, whereas a worn out one seems to be around the $500.  What is the cost or a full overhaul ??  Also Is there more value in getting a renisis over the 13B??   As I said I am hoping for  arounf 220 HP.  Suggestions please as Ihave less than zero expertise in this,
                                          Neil.

Worst case is pretty bad. You may need to lap the end housings and replace
both rotor housing and perhaps the rotor is damaged beyond repair.

This will cost about $3500 in the states. Both engines will make
about 250 HP at 7500 RPM after p-porting. If you don't be p-port
it you will be very lucky indeed to see 200 HP.

See if you can set up the engine with a bell housing and a starter.
Then take out both lower spark plugs.
Remove the schrader valve from a cheap compression tester and watch
the needle as the engine is rotated by the starter. You can also
use impact wrench to turn the engine over and a socket that will
fit the nut on the front of the  e-shaft. You should get three or
more equal pulses in a row of about 80 psi. Also the exhaust will make
a even popping sound like puf puf puf puf. If that happens you probably
have a pretty good engine. Look for something  later than 1989.

Probably the best way to buy a used engine is disassembled.

Sometimes one can find a cheap car with a running engine.

A late RX8 out of a wreck is probably a good buy as long
is it did not get damaged in the wreck.

Here is a cheap Chinese Wireless Inspection Camera not small enough
to fit in a spark plug hole unfortunately  but you can see part of
the inside of the engine looking through the exhaust
and intake ports with the 45 degree mirror it comes with.

Paul Lamar