“With the further most front inlet for this lock matching the touch hole location I will have to inlarge the sear bar hole moving the lock back. This will put the touchhole about 3/8” to 1/2” in front of the breech plug.”
That’s quite a distance to have between touch hole and breech plug (a small powder charge will not work in such a setup.)
I haven’t built their Trade gun but I did have alignment issues with their Tennessee Classic kit. The lock was too far forward (or barrel too far back) by about 1/4”. I solved it by adding a matching wood shim/spacer behind the breach (NOT by moving the lock or hogging out the lock mortise) and it worked great.