VVR for a JMP 1987

[dass101]

Hi guys,

I'm trying to figure what's the best way to install a VVR to an 1987 JMP Marshall. This is most likely a question for all amps with a choke in the power supply.

I know there have been some threads touching this subject, but none of them gave me a clear direction.

What I want to do is scale the PA and the PI, and conserve as much as possible the filtering and voltages for the preamp.
I'm really not sure where should I tap the B+ voltage and install the diodes and the VVR. I also don't know how to setup the plate and the screen voltages, it looks to me that the only way to do it is to use a dropping resistor between them - how should I estimate the correct value?