[Amps] N1BUG Ampli

[said sidate]

Hi 2 all
        I want to built the N1BUG 2m amplifier.Instead
of the 25pf/15kv vaccum variable capacitor for C9 i
want to use 2 flat "sandwich" made of two metallic
plates ---50*130mm---.
For C10, i want to use 2 flat "sandwich" made of two
metallic plates ---50*80mm--- with a movable plate
connected to the output N connector.

The two plated capacitors will have a U form at the
end of the anode line and will be vertical.
The 2 capacitors will be made variable by 2 teflon
rods.

The capacitor c9 will have almost 12pf.
The capacitor will be equal to 4pf.

Pse , are the 2 capacitors values sufficent for the 2m
ampli.
Will the U form not make an electric arc knowing that
the nearest cover will be at 20mm (at the anode line
end).
Tnx for ur help.
73s de CN8LI/Said.