While others have gone with trying to come up with something that would meet your stated aims, the question has got to be asked.
At some point, probably sooner than they would like, this aged PC is going to fail and you will not be able to operate the quality control device (whatever that is). So, no matter how taboo upgrades or modifications might be, they would need to find a solution to the upgrade of this device at some point. If production is relying on this PC it will need to consider the update path sooner rather than after it fails, when months of work might be ahead of them.