Newbie: red flags when shopping

[afterglow]

I'm going to be taking a look at a 69 Stepside in the next few days. Owner says it has no rust, complete, discs and coils on all corners, tilt wheel.

I'm a newbie and would like to know what should I look out for in terms of problem areas. I've been needing a parts hauler for a while but the plan is to shave and slam, nice wood bed, custom paint and full custom interior.