Regarding if the trim tag should or should not be removed during restoration depends on several factors:
1.) Can you be absolutely sure it will not be taken by someone at while the car is in the body shop?
2.) Can you be absolutely positive the tag will not be damaged during the restoration?
3.) How much rust is there behind the tag...a small amount is probably okay.
4.) Your person comfort level leaving it on and how much you trust the body shop/person you are dealing with.
When I restored my '69 Z28, I first purchased some NOS rivets used to reattach the tag. Before removing the tag I photo documented the tag, the original rivets along with the amount of seam sealer was used to close off the rivet holes.
After reading a few horror stores how some folks' tags were removed and stolen, I removed mine and kept it save until after the body was primed and ready for paint and firewall black out. I also wanted to reproduce the natural body color and firewall black out overspray on the tag.
Just my 2-cents worth!
