1977 F150 4x4 crank no start!!
 

You need spark, fuel, compression. Make sure you're getting spark(they make a spark plug tester pick one up from any auto parts store), make sure you're gettin fuel (pull fuel hose from carb and put in ext can and crank engine, see if fuel came out... or just make sure carb is squirting fuel when you flap it back and forth), then do a compression test (again auto parts store have this for sale and some even rent) Most of the time a vacuum line isn't going to keep your truck from starting.

Another thing to check is to make sure that the distributor drive gear is good.

Pull the distributor cap and crank. Make sure rotor is turning. Learned this one the hard way.

Good point, however that's one step I'd point him too once he checked for spark lol (yes you can do it before but if you checked for spark and had spark you know that part along with many other things is not your problem, but if you just checked the drive gear you could still have a spark issue) I'm just trying to keep him on a simple path to diagnosing engine problems.

Multiple easy things to check... however go thru the first 3 steps and then you can pin point which quick checks to look for before having to dive deeper into the engine.

Your carb is smoking? Sounds like you've probably got some decent carb problems and it needs a rebuild/replace. If you carb is all messed up like that, you could spend a whole bunch of time trying to diagnose issues that a simple carb rebuild/replacement would fix.

Check spark and fuel first though like has already been said.