Hi PhilAmerica, I don't know if you're still checking back here, but I thought I'd reply just in case. We have a Sabre 34 Mk I, so I'm not familiar with the really specific Mk II issues. However, all Sabres of this vintage with a keel-stepped mast had the possibility of mast step problems. Moisture gets caught at the mast step without proper drainage. Often you'll see discoloration/wet/rot in the cabin sole around the mast step. Sometimes you won't see any problems with the sole, but yet there is still a mast step issue.
My recommendation would be to find a surveyor who is particularly familiar with this specific issue in Sabres, and therefore knows what to look for.
Even with this potential issue, Sabres are great boats, and ours sails wonderfully.
I hope that helps!
1984 Sabre 34 Mk I