Wrote this morning and awaiting a reply.I have not built one. However, I would like to point out that Chambers also makes an English pistol kit, in addition to the Colonial pistol you have pictured. They haven't updated their website in years and years, but if you look at their pricelist, you'll see the English pistol on it. If you email them and request more information, Barbie can send you a PDF with a full description and pictures of a completed English pistol built from their kit.
I contacted them 2-3 years ago to ask if their pistol-sized Queen Anne lock could be fitted to the Colonial pistol kit. The answer was a cordial but firm "no." I was also interested in finding some double-set triggers for this long-barreled pistol, but came to a sort of dead end on that, too. However, I did have some interesting correspondence with Mr. Chambers regarding southern "bear pistols."
Sorry about rambling. I hope someone can provide the information you seek.