[JC455]

Hard to say... consider this:
If you replaced the floor pans- complete- is it still the same car?
What if you had to replace one of the quarters- still the same car?
Oh no, the other quarter has rust too! Same car?
The rear bumper needs to be rechromed- yours is used as a core, so it's gone...
You want to fix the holes in the firewall.. same car?
At this point, you've done what you're proposing... I guess it depends on how it was done- if you slice the donor 'sheet metal' at the B pillar and upper firewall, then make the same cuts on the Judge, then weld it together, it's getting really close to doing a re-body.
Yet those same panels, done one at a time, constitute a restoration.