Found a peanut, Found a peanut, Found a peanut just now!

Do not cut the harness to take it out. In fact, leave it on when you pull the engine so you know where everything goes.
There should not be any trouble with the PCM due to the rollover unless it's physically damaged. There was no fuel cut feature that I ever came across on these.
I have let Magnum trucks sit a long time before starting. A couple alternators and an idler pulley rusted and wouldn't spin. One caused the engine to not crank over at all, the others started but had tons of belt noise. Check it before starting.
The lifters often bleed down after that long. It will require a little cranking and often a little throttle manipulation to keep it running, but don't worry it will smooth out.