Congrats on the M37 acquisition they are good pickup, simple, easy to work on pretty reliable if maintenance is kept up on! Depending on what you know about this trucks history something I do to all my trucks when I get them is to drain all lubricants including diffs, trans and transfer case, look at the coolant and depending on its appearance you can decide? Then I would go over the drive line checking all the U-Joints and if they look good then give everything a good shot of grease and I strongly suggest you get a set of TMs for the truck they are absolutely full of wonderful information! If the truck is starting good and idling good I would leave the ignition and carb as is. You do have some leaks underneath I would clean up those areas at least to the point that as you drive the truck you can see any new oil drips etc, then you can decide if they are serious enough to tackle and fix. As was mentioned above the other areas your going to want to look at are going to be the fuel system including sending unit, fuel lines and fuel pump and filter. A lot of these trucks had electric pumps installed in them when the factory pump went bad, the electrics work very well. Fuel lines you need to know condition since they are all steel and rust can be a big issue. If the fuel gauge works your sending unit is good but keep an eye on your fuel filter for bad sediment from the fuel tank, it may have to be cleaned and possibly relined?
Good luck and Congrats once again!
Karl