Kay 730-c upgrade for guitar

[PRNDL]

I am upgrading a Kay 730-c for guitar.
It's the one with unusual tubes - 18GD6A, 60F15 and 36AM3.

Yesterday, I put in a Triode N-64 isolation transformer and replaced the electrolytics.
The hot side of the transformer output goes to V3, and the other side goes to ground, as does the isolation transformer. The switch is now on the line input. (That seemed a bit complicated to figure out to me).

Today I'm considering what to do with the preamp tube (18GD6A) and input jacks.

The simplest change to the input jacks would be to remove C1 and R2 and put a wire from R1 to the grid.

The preamp has a grounded cathode.

Is it recommended to change this to a cathode RC?
If so, what values for R and C?

The data sheet puts the plate resistance at 500K and recommends a 150 ohm resistor.
R4 (the anode resistor) is 680K.

Any other recommended changes?

Schematics are here
http://www.schematicheaven.com/bargainbin.htm

[PRNDL]

It sounds awesome!

I decided to see how it sounds without adding the cathode RC, before making changes.

The amp begins distorting fairly early, which is what I'd expect with the preamp tube getting hit pretty hard. But, it gets a really nice raunchy distortion on 10.

The next issue is whether to put on some new black tolex. It's got a lot of tears and dings into the wood, but I wonder if that is part of the charm in this little amp -- 1 watt of major mojo.

Any suggestions/opinions?

Thanks!!

[PRNDL]

Photos are here

http://www.naturdoctor.com/Chapters/...ay703/Kay.html