I have one of those old shotguns.
The Marlin 410 is built on the Marlin 1893 rifle, so perhaps a 93 rifle buttplate would work. This would certainly be more available than looking for a specific Marlin 410 buttplate.
Dang ... hang on a minute ... yer gonna send me off to the gun safe, aren't ya? ... <grumble>
Back. Dug it out. Yep, buttplate is hard, black rubber with Marlin on it. Got to wondering if it had Marlin 410 on it, but no. Just Marlin on it.
My shotgun's apparently a very early one, with the serial number of U5XX. Even perusing the big Marlin book by Brophy has failed to reveal what that U prefix means.
You may wish to check Dixie Gun Works or Gun Parts Corp. for an original, rubber buttplate.