RE:70's silver faced Princeton Reverb: looking for clean headro

I have a mid 70's  silver faced princeton reverb. I play a 335 style semi hollow with humbuckers (lowered appropriately/ not too hot). I'm looking for a speaker option that will give me more clear headroom. Testing out a Rajin Cajun and it craps out on the low E and E string. Really want to be able to play a single note or chord and retain clarity. I'll use a pedal to add overtdrive when I want it. 

Suggestions? 

Easy!  The G12C!

Also ... are your filter caps new/healthy?  That's a big part of "clean headroom" in a vintage amp!