What sort of plate and screen voltage? 3k3 is kinda low.

398v plate and 24v screen IIRC

That seems a little low for the screens Do you mean 240V? My initial guess is that 3k3 is going to be a bit of odd choice for that plate and screen voltage (assuming you mean 240V, I have a sheet with a 250V screen which is close enough) as the load line will pass through the 0V curve above the knee which is great for a linear triode like hifi sound but lacking in compressiony goodness we like for guitar. You can knock the screens up though and at ~400V you could use a choke to have the screens and plate be very close together and then use a 2k screen resistor to stop them getting all melty (1k is probably still fine though, depends on who much screen compression you like) and this would pass the load below the knee for a less clean power amp. If the screens are at ~250V then 6k6 would still be a reasonable primary impedance for good below the knee operation.

I'll draw up some load lines later so this makes a bit more sense.

Nope, definitely around 24v, on the cathode (i shouldn't post tech info when I'm sleepy), Screen voltage is roughly around 375v.

Blame sundays

It certainly could work but I'd have a keen eye on it at all times and running into a lower load is usually safer as while you're asking a greater current demand from the power supply you also reduce the fly back voltage from the class A part of the load line. This is why mismatching the otherway is bad as you increase the flyback voltage and put more stress on the screens but I'm sick of explaining that on HCAF and they can blow their amps up if they want

My thoughts would be that the power amp might sound a little hifi/sterile as the grid curves are much more linearly spaced when you intersect the 0V curve above the knee but that needn't necessarily sound bad. It may be necessary to use a colder bias though as the class A part of the load line must be below the plate dissipation curve or it'll redplate. I'll have a pop at drawing the curves for that screen voltage later as its something I do need to work on.

I totally still havent drawn those load lines! I can do basic diode curves but I want to do the real thing to get the knees right.

Include the math please!!!

Well I'm back from visiting family over christmas so I'll go over this. You can do it mathsy but that only really works if you're fudging by 10's of volts. For big boy shifts you need to read off the mutual characteristics curves which aren't always available or require a bit of guessing.