Some here may scoff at this but..... We do what works sometimes.

My 89 T/A with VATS had a bad ignition cylinder. Rather that do the VATs dance, here is what I did.

I purchased a regular/ non-VATS ignition cylinder.
I removed the bad cylinder (the tumblers were worn out).
I cut the 2 orange VATS wires and pulled them out of the steering column, set that aside for now.
I installed the new non VATs cylinder, and put the steering column back together.

To check my work...Insert the new key and turn on...the SECURITY light comes on...but stays on. Indicating the ECM didnt rceive the ohm reading from the original key.
......
Heres the ******* part
Under the steering column, I re-attached the 2 orange wires, soldered, and taped them up (with the old, bad cylinder still attached)
I put the original key into the old cylinder and taped it into place.
I used zip ties to secure the old cylinder under the dash, to tidy things up...replace the under dash kick panel.....

DONE!

What I have is...
The original key is ALWAYS inserted into the original cylinder, stowed away under the dash. My new, non-chipped key works like any other non-VATS key.

 

I disabled my VATS by measuring the resistance of the key, disconnected the plug from the Ignition cylinder, got a resistor (or a couple in Parallel) to measure the same and soldered them to the ECM side of the connector. Now the car starts fine all the time.

 

Somebody did the EXACT same thing on my first camaro a 90 rs. We noticed the lock under the dash with the stock key. Then I would start the car with the aftermarket key in the column. Adam :-)

 

if you were already doing it along those lines

it'd be just as easy to just chop the excess off the OEM key leaving just the resistor, and soldering it into place.