advice on GFA2 rebuild?

Hello from a newbie so pls forgive transgressions in advance...

I've got an Adcom GFA2 power amp, 100w/ch which has intermittent dropout problems independently in both channels, about 10% of the time...

but that doesn't matter because I've decided to rebuild it hopefully using the existing power supply, heat sinks and replacing the electronics.

The voltage across the filter caps is 58VDC if that helps.

It will be used to drive 6ohm 2 ways (scanspeak drivers), about 92 db efficient, and most of my listening is low power. I'm using a passive preamp from a ROtel bx940 cd mainly.

Sound quaility is ahead of all other considerations.

Any advice on where to start for a simple circuit, what transistors to use?