Sorry to hear about the car crash..
Hope that you have recovered.
I believe that you will find that in your 757 example the increased weight was due to lower screen height and use of thrust reverser for stopping, not a different VMCG as you don’t have contaminated/dry VMCG’s.
If you compared different ratings, then you might get better contaminated weights with a lower thrust ratings depending on the runway length, we do this all the time to get out of JFK, the wet check just stops the benefits of the screen height/thrust reverser credits
Mutt