use Subaru/suzuki -justy running gear perhaps,
done that swap a few times now with a few different cars.
swaping floor pans would be the simplest and cleanest route ( ok maybe a slight VOSA issue ) but i would argue that you could not find an original floor pan so had to make do with what you could get
the other option we have done is just replaced the boot area floor pan section to allow rear suspesion/diff ( some cars do not even need knew exhaust tunnel)