Definitely have as full survey done as possible.
My brother recently went through this with our '71 Cheoy Lee 42. Had he done the full survey (involving unstepping the masts and an engine survey), he could have saved about $8,000-$10,000 in unnecessary expenses. Nearly the entire standing rig needed replacment and the engine required about $2,500 in repairs as well.
A full survey is a VERY VERY good idea!
/s/ Jon C. Munson II