No it's sacrilege!
They must be kept as they were, that's the whole point of keeping something from the past.
The numbers of original historical cars are so low they can be forgiven their emissions for their infrequent road trips. As long as just one coal power station remains it's insignificant anyway.
By all means build replicas with EV power trains, that's a great idea but don't cannibalise any surviving genuine classic or vintage cars.
