Dave,
Here are some photos of an English trade gun I have which may be of some help to you in you restoration work. Dimensions are:
English Trade Gun
LOA 52.25 LOP 13.25
Barrel LOA 37.18 Breech 1.22 Muzzle 0.72 Bore 0.56 Marked LONDON plus English proofs
Buttplate H 4.75 W 1.75
Lockplate H 1.18 L 6.25
Rear ramrod pipe to middle ramrod pipe 11.25 (this is the length of visible ramrod)
Middle ramrod pipe to front ramrod pipe 7.25 (this is the length of visible ramrod)
There are more photos of the brass mounts and the engraving, if you want me to post them, let me know.
A few notes.
1. The barrel was shortened by about 6 inches or so, the front on the wood looks like it was cut with a hatchet.
2. The front ramrod pipe is copper, with obvious hammer marks.
3. The sideplate outline is more usually engraved as a dragon, this one is floral.
4. The ramrod and tip are certainly replacements.
Jim