Gah, if it had some kids grubby hands in it I would not run it till I had it back apart and put back together correctly.
Never know if a retard dropped a bolt down the timing case or something REALLY important, maybe didnt torque a bolt that holds the guides ect. Would hate to find out the hard way.
I recommend an engine stand, a FSM, a torque wrench, loctite, good lighting. You wouldn't have to pull the WHOLE engine apart (like the bottom end).
But I would personally strip it to a short block, inspect mains/rod bearings 1 by 1. So take it off, inspect lower half shell of bearing, put back on, torque. I would also put in all new OEM timing equip like chains/guides/sprockets if need be.
Have the head on a set of head stands and inspect the surface for cracks, valve seats for leaks/debris.
All of that is mostly free (except putting new parts where necessary) and will learn you A SH*TLOAD!
I guess if you cannot do that then the next best thing would be a leakdown test at the bare minimum to see if the cylinders will even hold compression before you stick it into the car.