Some of these capacitors in the driver cascode have almost a supply rail across them, so the upgrade from 50V to 100V might have been due to higher supply.
Any 330pF 100V of decent dielectric will do just fine.
This one is COG, so excellent
https://my.element14.com/vishay/1c20c0g331j100b/ceramic-capacitor-330pf-100v-c0g/dp/6525404
Any 330pF 100V of decent dielectric will do just fine.
This one is COG, so excellent
https://my.element14.com/vishay/1c20c0g331j100b/ceramic-capacitor-330pf-100v-c0g/dp/6525404