OK, sounds like progress
First, do you have the Owners Manual? If so, look to see what the fuses are and maybe for anything else missing...
Next, the OBD-II connector is what the scanner plugs into and is located somewhere below the steering column but, now that the PCM is running it's not something I'd bother with yet.
So, now there's something still not right..... but, the truck's been sitting for a while - right
How are the batteries? Fully charged? (it will NEVER start if it's not cranking normally)
Fuel, is the filter housing full? Can you see fuel coming from the water drain if you open it? When you first roll-on the key do you hear the pump running for a couple of seconds? (on the frame rail below the drivers seat)
Oil, believe it or not
, the truck is designed not to run if the engine oil is too low.
When you're cranking does the tach needle come-up a bit?
I'm puzzled by the missing fuse,,,, what happened? You said the heater was blowing the fuse, but what fuse was that if not #30? (maybe you just got mixed-up and put the replacement in a different place?)
At some point, if everything else looks OK, you've just got
to get a scanner on it to look into what's causing the no-start. Unfortunately, it's a "special" scanner that not everybody has and you'll need to seek out someone with the right equipment. Often a local member can be found who can help you depending on where you are.