and... the Churchill, El-Grande (and if you make just one cap bushing, the El-Grande Streamline too) share the same bushings.
For the Churchill/El-Grande, I would go with AZ Supply or Beartooth Woods.
CSUSA is the only place for the Gent style. Just be warned, the Gent is a LARGE kit, and even for me, who likes large kits, think it's a bit "too big" Mostly in the length, I could deal with width & heft.
I say look at the Jr.Gent / Retro / Jr. Statesman as one bushing style, but I have a set of the Jr.Gent twist pen-pencil in the shop now to fill an order and I think these are awesome for a pen/pencil set and plan to make more. Very nice pen for those who do not like the rollerball refills.