You should use the computer and harness that goes with the 5.3.
That harness that was cut, it is just a pass-thru, not a connector.
The other side of those wires goes to connectors behind the right side kick panel.
What you are taking on is not trivial, but doable. What you want to do is marry the two electrical systems. You need to be one part detective and one part electrical engineer. It helps if you get the entire electrical system from the donor, so that your vehicle thinks that it is a 2001 Corvette, not realizing it is in Caprice clothing.
The 2001 Corvette factory service manual and the 95 Caprice/Impala SS/Roadmaster Factory Service Manuals will have the electrical schematics to allow you to determine what needs to be grafted in and what can be used of the remainder of the Caprice system.
For instance, the '95 Caprice PCM gets info from a pressure sensor in the AC system and uses the pressure info in its decision as to turning on the radiator fans. I don't know how the Corvette does it.
Good luck with it.
95 9C1, Sold 2009, 203K miles, PCM by Me and Tuner Cat, Meziere water pump, Roadmaster blue leather interior