since you live in sweden, what does your DMV say about vin problems ?
That is the answer right there.
The legal VIN is the tag on the dash, not the stamp in a cowl. So here, at least, what you do with the cowl is irrelevant for identification purposes.
What some can't seem to grasp is that taking that legal VIN tag off the dash from a rusty, wore out, tore up, no longer salvageable "collectible" vehicle and putting it on a "donor" is what's illegal. Not fixing a rusty cowl.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.