A quick measurement reveals the following regarding the thickness of these feet measured at the very end of the foot from the INSIDE the curve to the outside of the curve:
Original 1950’s version Medalist 1494 foot - .032”
OnePfoot Original replacement Medalist 1494 foot (Silver) - .044”
OnePfoot Original replacement Medalist 1494 foot (Black) - .044”
The thickness further up the foot about where it would bottom out in a reel seat hood is a little trickier to measure, but in all of my attempts to measure that, the original Medalist foot is thinner or should I say, less thick with a shallower rise.
I don't know if it matters but both of the OnePfoot feet I measured were bought directly from Bill Franke and while I assume the Dan Hill versions are identical, I can't be sure because I don't own any.
Unless I am missing something, if the reelseat in question won’t accept a standard Medalist foot as per Doug’s original comments, it probably won’t accept either of the OnePfoot replacements.
I don’t own a Martin 61 to measure but it would be interesting to see how it measures up.