What year is it???
The VIN will tell you.

That will help you with a lot of your wiring questions.

YOU WILL NEED WIRING DETAILS FOR THAT MODEL.

"Vortec" is just the heads, and there are several editions of them, not interchangable across 1995.
Usually the valve covers will say "Vortec" if it is.
Many exceptions, though.
And I think after ~1998 most 4.3's were "vortec" heads (?).

Looks very much like a TBI injector?

Don `87 Mitsu 2dr, Rubicon survivor, GModified.