Sybunt and Lybunt Report fields
Agreed that the correct solution is to work within getBasicContactFields(), but since your question is a good one with a more general application:

When you add organization name and prefix, you're doing so by adding them to the class's _columns property.  As you note, this doesn't look up "pseudoconstants", such as converting prefix_id to a prefix.

That happens in the alterDisplay method toward the bottom of the same file.  Here's a good example in the Lybunt report of using a pseudoconstant lookup to convert the gender ID to a gender:

https://github.com/civicrm/civicrm-core/blob/master/CRM/Report/Form/Contribute/Lybunt.php#L719

Hopefully this example is what you need; otherwise feel free to comment/update the question!