Must be a full set of the 3 on eBay though then get that map onto that new ECU
Yes that is only a plan if the new stuff can be programed to the car with the opcom laptop software
If you buy a matched set of the three parts, you don't need to program anything, they'll just work.
You'll also need to make sure you either buy a matched set of VX220 ecu/transponder/key chips. If you get a cheapo Vectra/Astra set you'll need to get the firmware reflashed with the VX220 configuration (unless you want permanent EML's for faults in the missing aircon or powersteering). I think Courtenay can upload a proper VX220 base configuration with their TECH2. Alternatively, people like the ECU Doctor on flidBay can do it.
Whatever you get, your SC map will have to be reloaded onto this new ecu by Courtenay/Klassen, not something that can be done via Opcom.