Contacting Car's Original Owner

[ZLP955]

Well after years of trying to track down my car's original owner after he moved, I recently found a new lead which has led to a new address and phone number half way across the USA from where he originally lived and owned/raced the car.
Before I pick up the phone, just thought I would ask any of you who have either already done this, or have been in the original owner's position of getting a cold call from a stranger (especially one 'down under'), what works well and what should be avoided upon initial contact?
Don't want to freak him out, but naturally I'm excited at the possibility of making contact at last and learning ANY new details about the car. Photos or paperwork would be icing on the cake but I'd settle for a good chat; Hopefully he has total recall