don't worry about the rivits, get the correct vehicle vin on the dash you install. if any issues arise, the frame, engine, firewall, window and MANY other hidden vins will show you are not breaking the law.
is it possible to remove the dash on that car and leave the vin portion of metal in place? if not, then you have to do the right thing and keep the correct vin plate in it's location.
if you are worried about it, go to any body shop and ask what they do with replacement dashes that come without any vin... I bet they drill and pop the right vin plate onto it.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!