If that is a proper, period correct, recoil pad with the legend "PAT. APPL'D FOR" at the bottom of the logo on the face --
00001. Ithaca Bridge Trestle pads.jpg
I'd do everything possible to save it. The repros are of the post war style with the word "PATENTED". From its introduction in 1932 through the end of NID production in 1948, the Ithaca "Bridge Trestle" Pad was only offered in the medium size. NID Magnum-10s, if found with an original recoil pad, usually have a seven-slot Jostam Anti-Flinch or a 15-heart Hawkins. By 1950, when they changed to the aluminum base of the pad it was offered in medium and large. The repros from Kings Ferry were offered in both sizes.
Have you had a chance to weigh your new toy? I have a similar 1941 vintage No. 4E, 16-gauge, 26-inch, ic & mod, that is quite the little chunk at 7 pounds 2.6 ounces.