Hi Bill,

I am a proponent of "if it ain't broke, don't fix it." if you have some
history with the mechanical device in question.  On the other hand, when
that history is unknown, not knowing can bite you.

I bought a "Brand New" 13B - trouble was it had a bit of water in the
coolant jacket, which corroded the iron castings.  Everything in oil looked
brand new.  The coolant passages were another story, after bead blasting the
coolant passages until they were clean I did a bit of destructive testing on
the castings with a dremel, just a bit because they looked fine...  a minute
later I was pretty dissapointed,  went through like butter in some places
( like near the coolant o rings), just turned into black dust.  $1500 later
I think I have an engine that is as good as it is going to get.

Don't be put off working on a rotary, these engines are easy to work on, buy
a couple of good torque wrenches, a box of sandwich bags, a sharpie, take
pictures as you go and take your time - try it out on a junker 13B the first
time to build confidence.

Even factory rebuilds have the occasional issue - I apprenticed at a Porsche
/ Audi dealership.  I witnessed a $25,000 (1980 dollars) 3 litre 911 long
block throw a rod in the first couple of minutes after start up, missing
connecting rod nut on one side of the cap - sh!t happens.

FWIW

Ian