I can't help you with your choice of what to build but I was at the same stage you are about a year ago.
I started at looking at "off the shelf" rifles (Pedersoli, Lyman, T/C). Thought some were "ok" but could be "tweaked" a bit to better fit my taste.
Then, like you found TOTW etc and figured a precarve/pre-inlet and a "box of parts" would do it for me but ended up not totally liking the restrictiveness of the pre-inlet (what if I wanted a different lock to look more like a specific builder?).
So next looked at precarve - shaped with barrel/ramrod inlet done but not the lock, trigger etc.
Ended up figuring if I could go that far may as well just pick up a chunk of maple and go at it
To be fair I already had a fair bit of woodwork experience and all the tools so that part wasn't too scary - it was more fitting the breech plug and cutting a patch box from scratch - stuff like that, that seemed daunting.
My suggestion to you would be look for a "level of completeness" that you are comfortable with but you will still find challenging to build/finish as the case may be. The less that's done for you the more of your own flavour you can add to the build unless you are going for a (copy) as close to a specific original as you can get. If you are simply looking for something "in the spirit of" or a "generic" New England gun you may enjoy doing a little more than simply cleaning up an inlet and bolting the part in.
At least from all the prep work you have been doing I get the impression you may not be totally satisfied with a "ready to assemble" piece if it doesn't challenge you.
For me it was all over when I saw a Daniel Marker fullstock rifle that he built during his days in Ohio. Saw that National Roads patchbox and just had to have one - no "kit" available, so I got out the saw and the chisel