We are taking the thread off track, but ...
A short time ago I made a similar inquiry about cored hulls. To summarize: Coring makes the hull
light and strong if done correclty. A good surveyor
will be able to detect delamination
and/or rotting of the core
below the water
line. A thru-hull on a cored hull is a potential point of water
ingress on a cored hull if not done right. When the hull was laid it up there should have been solid glass at the points where a thru-hull was to be installed. If thru-hulls were installed after the hull was built then at the point of the hole the core
should have been taken back far enough to put in epoxy
and seal the core material away from any possible moisture. My own sense of things is that the older the boat, the more likely it is that there has been moisture ingress unless you know explicitly the history
of the boat and its owners.
As for rod riggning, there are pros and cons which I will let others address. But, once again, be aware that everything wears out over time. That is why a good surveyor