I know the museum likes to maintain authenticity, but vinyl lettering will last 5-7 years while hand-painted lettering will not look good after two. I know. When I worked for a sign company, I re-painted our sandblasted sign with imitation gold and it didn't hold up anytime at all. Vinyl is so thin that it will look like paint to anyone over, say, two feet away. On the other hand, our company's owner told me that if it were up to him, he'd do nothing but hand paint signs all day. He loved it.
Jock Ellis