Doing ANYTHING to "improve" the appearance of a survivor is a VERY bad idea. You will essentially be erasing history which is what makes a survivor so special. People that will be interested in a survivor car appreciate and understand the fact that they aren't always "pretty", that dirt and wear are signs of a good honest original car that hasn't been messed with.

Here are a couple survivor Hemi engines. True survivor fans go nuts over engines that look like this, they don't need to look pretty to impress.