Very unlikely.
It might be possible with some tinkering and careful planing, but simply plugging the disks in a new PC won't do it. I did that many times at home (plugging the old WinXP HDD into a new motherboard) and never worked. Mostly, that gave a blue screen.
You need to take into account the following:
- conectivity (e.g. nowadays is hard to find a motherboard with a serial port onboard)
- BIOS ---> UEFI
- MBR ---> MPT
- Single core -> Multi core
- Drivers
- Any license keys for you SCADA programs (some license keys are hardware locked, and can read unique IDs like HDD ID, Proc ID, Bios ID) etc.
- Risk management (e.g. how critical that SCADA system is, how much time do you get, if any, to test the new system, will they sign an acceptance test for such a hack, is it legal to transfer the license)
I worked for the power grid, and implemented a few (tens of) SCADA systems. Here, even if it were possible to just transfer the disks, such a solution won't be accepted.