I have to add a bit of a correction, I confused Track's Issac Haines kit with their Bivins kit. Their Isaac Haines kit has a much more fully shaped and inlet stock, similar to a Chambers kit.
Their Bivins stock, is left square forward of the lock panels, so yes, there is more wood left on that one.
I know kits seem to be all the rage now, but you will learn much more and your skills will progress further if you take on building from a blank. There are people out there who are able to inlet your barrel into a blank and even mill the ramrod groove and drill the hole if you desire. I don't have their names on the tip of my tongue, but a quick search on the site should turn up a couple of them.
Good luck.