PETSCII to ASCII tool

Here's what I did in my editor:

If the PETSCII character is A-Z, make it a-z (PETSCII 97-122, subtract 32)
If the PETSCII character is a-z, make it A-Z (PETSCII 65-90, add 32)
If the PETSCII character is 192-223, subtract 96. Then subtract 32 if the resultant value is 97-122.

And here's another fun trick:

A group called "Style64" has created a TrueType font that maps the PETSCII character set both as screen codes and in the PET ASCII order:

style64.org/petscii/

If you add the PETSCII value and $E000, you'll get a Unicode character that matches the PETSCII symbol. You can then write that back out as Unicode text and load it up in a text editor that can handle Unicode.