I own a '67 Suburban and '85 Chevy 1-ton, have owned several other carburetor-era vehicles in the last 10 years, and restored a Jeep CJ7 this year.
It is a rare seller that is being fully honest and considerate of the buyer's concerns, and is fully aware of all the vehicle's problems. If more people undertook to own and thoroughly maintain pre-1990 vehicles the motoring public would be better off (from the standpoint of knowledge and skill) so I fully support that, but a 38 year old truck that "needs a few things" should be interpreted as "project that you'll be hard pressed to make a profit on if you're concerned about its value, and needs repairs in 80% of the systems to be reliable". In the group of folks prone to wrenching on '79 Fords there are far more people than not that, if the vehicle doesn't run or drive right, it's probably due to their lack of care or skill.
There's an exception to every rule, but 99% chance is the thousand dollar truck will require another thousand or two, and months of tinkering, learning, re-fixing, and much perseverance to be really decent. If you're up for that, go for it.