I have the W8 hard drive but the W8 laptop is scotched (liquid spillage - mechanic says motherboard caput).
I don't have another working computer - and the mechanic seemed unwilling to accept the challenge when I offered him the original hard drive.
He said that everything had been copied over to the new hard drive, however my simple mind suggested your solution - that the necessary profile would exist on the old hard drive.
He seemed fixed on the different operating systems - which I tried to question him on but he couldn't explain in terms that I understood.
I have in previous years built my own desktops from scratch with various Microsoft operating systems, and I imagined that the old hard drive would have the W8 OS still in place.
In the past I have used caddies with alternate hard drives - but desktop sizes, not laptop sizes.
Without hardware I cannot start to explore further.