Barker Williamson FC-30A is correct choose for most of linear amplifiers. Only one available any more.
Capacitors, Russian Military High Voltage Ceramic , Various Models KVI-3
Amperex 3-500Z 8802 Electron Tube / Triode
Variable Capacitor 4,5 KV, 16-310 pF
Ferrite Rods
Vacuum High Voltage Capacitors, also Variable 300 PF