WAD HD83 Mk1 mods ?

[Sgt.Pepper]

Hi,I recently acquired a WAD HD83 Mk1 which sounds very nice but cannot resist the urge to mod it slightly.First up would be the volume shunt and coupling caps and may as well replace the resistors.

My query is what and which rectifiers,if they are worth doing ,also does anybody have a circuit diagram with component values on it they can send me please ?

Trying to keep the mod budget under £50 so no new case work or power supply caps

Cheers
Paul