The Two Stroke really isn’t that amp but you could try a lower gain preamp tube (like a 12AY7) to get a little more head room. A solid state rectifier will add a little more headroom too. That would be a very simple installation, install 4 diodes on the open lugs of the rectifier socket.
But….if you really want more usable headroom, build a Spitfire clone.
The Two Stroke is a great little rock amp but it’s much the same as a Tweed era Fender in now it breaks up.