Masco MA-8 for guitar

I recently came upon a small Masco MA-8-N amplifier from the late 1940's that sounds really good and is in good shape. I've already put a 3 wire plug in and changed some of the jacks but I'd like to change some of the circuit to tailor it towards guitar. As far as tubes, it has a 6SF5, 6SJ7, 6L6, and a 5Y3 rectifier.

It seems like I could take a cue from the Fender 5C1 Champ circuit, which has basically the same tube set-up minus the 6SF5, although it seems like a shame not to use all of the tubes. Maybe I should think about wiring an extra gain stage there? I'm still pretty new to these PA conversions– so far I've only changed the tone controls of a Bogen CHB-35 thrift store find. any advice would be appreciated. I have a schematic, but if its ok to post it or whatnot...thanks!