4 Gauge To 6 Gauge Cluster Swap - A Little Help

I have a 2005 Mustang V6 that I purchased new as soon as they were delivered to the dealership. Unfortunately, it only has 4 gauge cluster. I have been reading up on swapping the cluster for the 6 gauge cluster. Recently I came across my original window sticker and found out that my mustang is a Premium, however the unused plug was not behind the button blank on the dash, but I have not looked to see if it might be taped up somewhere else on the harness. I would very much like to have the 6 gauges, and I am not very concerned with having the color changing gauges.

I have been going over the pinouts both the Message Center Switch (C253) and the Instrument Cluster (C220). The message center switch only has 4 wires:

1: illumination/power
2: switch signal
3: switch return
4: ground

The Instrument Cluster (C220) has 2 pins used for the message center:

6: message center switch input
7: message center switch return

I can get the cluster for under $100, the switch for under $30, and the switch harness plug for under $25. I can easily add wires to the cluster harness for pins 6 and 7. My question is, is it as simple connecting the switch signal and return wires to the signal and return pins on the cluster? I know that I will have to have the mileage and as built info adjusted at the dealership. I just know my luck, and nothing is as simple as it seems.

Please let me know what you think.

I am attaching the pinouts.