There are different injection systems on different engines and years and other external things, but it's difficult to know what's inside an engine because parts could have been changed over the years. That's the reason for Jeff's "unless it's been modified" comment, since after 40 years there aren't many engines that haven't yet been re-built, so potentially modified. The only dependable external tell is the three bolt heads of the 2.0 liter engine. The 2.0 engine used three bolts to attach the intake manifolds to the heads, the 1.7 and 1.8 engines used four bolts, one on either side of each intake runner. But even that isn't definitive, since the 1.7 and 1.8 heads can be installed on a 2.0 liter engine, and vice-versa, the 2.0 liter parts can be used with a smaller case. Or VW T4 car or bus engine parts could have been installed in the engine. So you have to either take the owners word or, to be certain, actually take the engine apart.
There's a good set of engine and part number identifiers at
http://www.tunacan.net/t4/index.shtml, look at the "reference" tab, then "crankcase" or "cylinder head" or whatever part you have, to identify where it came from, what it is. But obviously that isn't helpful until the engine's apart.
For colors, equipment, options, etc. check in the Pelican Parts Tech pages,
http://www.pelicanparts.com/914/914world.htm. He might be especially interested in starting at the "buying a 914" guide there, which has a lot of the info he'll need and links.