Is it an early M8 that had the hard rubber butt plate? or the later style steel cresent shaped w/the tang on the bottom toe line of the stock?.
If the first style and they only removed enough wood to flatten out the surface to install the existing pad,,I'd go ahead and install an original style repro hard rubber butt plate. They have a slight curve to them.
You may have lost 1/4" in LOP but the style will be correct.
Those old rifles didn't have much more than a 13 1/4" LOP to begin with.
If the latter type and they cut so much wood off to eliminate the butt plate tang cut on the bottom toe line,, then I'd go ahead and either put a repro Silvers or maybe even a NoShoc pad on it. Hawkins is another but I don't think it's correct for a rifle. At least they were styles available 'back when'. Galazan and others sell these recoil pads, They are about $30 and up.
The M8 was available w/a recoil pad as an option, but Henwoods book on the rifle doesn't describe or picture the type or style used.
A leather covered pad is a nice option. You can use most any solid pad as a base. A very thin leather for the covering, wet it to be able to stretch it around the pad and glue it to the under side. Or stretch it and pull down along the sides and glue to the rubber leaving the black spacer showing.
I used to use Kangaroo leather for this. Got hard to get after while as the Friends of Kangaroos crowd made it hard to import it or sell it.
Now I use thin scrap leather from womens gloves, purses, ect. Works out well. It's usually goat leather I think.
You could always restock the rifle.
