To Replace or Not to Replace

Generally speaking, is it better to replace the rusted hands of a vintage pocket watch or keep them because they're original? Does that also apply to the dial? I picked up an Elgin 345 Grade 3 and it looks like the old acrylic crystal is the culprit. I'm pretty new to pocket watches and I don't want to mistakenly destroy some wildly collectable watch, but if this will only fetch $90 in mint condition I probably don't want to spend the money anyway.