He'll relax after a few days man. Just treat him with respect, as you do her I'm sure. Eventually he'll see you're a good guy and it'll be water under the bridge. Leave your phone at home and go out for a ride with the windows down and blow off some steam.
Seems like its damned if you do..damned if you don't in this situation. I'm not ok with VIN swaps, jmo.
Hell if you're gonna swap VINs, just open a chop shop.