RC Germany,
I also think that +60hp could be too much but....who knows???
I tend to believe that the engine could be available with the same power as of the GT Endurance cars, i.e. 420hp
This looks more consistent with what you heard about the GT3 upgrade (415hp)

I have to speak again with my dealer mid this week. I will ask him to chase more Porsche AG to give us more to talk about

Ciao,
Andrea