This proves that all the gunk on the intake is from before - this engine has been sitting ~4.5 months and the valley almost looks fresh-from-the-crate.
These intake gaskets only have ~30Kmi, but the coolant system was severely abused & neglected, which is why the gaskets are in such horrible condition around those journals (the 4 frontmost & rearmost).
.
.
This was the truck's original engine:
