If it has a mild steel bulkhead, check the foot wheel corners and below the line of the wing from underneath.
Worth seeing it on a ramp if possible to check the chassis for dings, cracks and rust.
Check the sill boards for damp / rot.
Always worth checking how well the doors close - in case of worn hinges. Unlikely to be ash problems on that era as it will have been cuprinol treated from new.
Our previous Morgan was from 1985 and definitely pre-galvanised chassis - there were no problems on that one up until 8 years ago when we traded it in on the current car. However, we know of a year 2000 car that has had a crack in the chassis.