The PL is a great integrated amp-as is.
4 premium caps and # resistors + labor probably will eat $500+ easy?
Unless you're Bob Carver, no amount of modifications will turn it into an ARC, BAT or whatever killer.
https://www.stereophile.com/content/carver-challenge
Put the PL in a second system or sell it.
The PL already has a low resale value. Mods will lower it.
Longtime PL user here.