Note that's it's not a recoil pad - but he may be able to make one a shade longer than standard and you could use a belt sander to sculpt a pachmayer pad to fit in the crescent. Drop him an e-mail and ask (the laced style looks more authentic on lever-action rifles). He'll do plain or ornate, take a look at the examples.
The only other option is to find an 1886 buttstock replica and have it modified to fit a shotgun-style pad. Store the original while you enjoy the rifle.
I guess you could also use the Past gel recoil pad that straps to your shoulder (popular with the guys who shoot clays all day). Nobody can see it under a field jacket.