Toyota Repair: Check Engine Light - How Serious?, independent mechanic, valve job

Question
Ted,  I am considering the purchase of a used '94 Toyota P/U with the V6 engine.  The seller has been very honest and tells me the 'check engine' light came on right before they were going to put it up for sale.  The Toyota dealership and another independent mechanic tell them that it needs a valve job.  They also strongly encourage that it not be driven due to possible engine failure.  The problem is that the truck is 800 miles away.  Is there a real danger of driving it home?  Could it be something simple like a sensor?  If we have the valve job done at the seller's location, what else should we check for to assure a sound engine?  The transmission, clutch and timing chain were all handled about 20K miles ago.  Thanks.

Answer
I can't be of too much help because I don't know what the trouble code was that made the check engine light come on,I have no idea whether it needs a valve job or just a tune up, I would tend to agree with the recommendation to not drive it for 800 miles under this condition.