"here are the instructions for 53 Ford motor mounts, see if they look like your Merc. When I jacked up the motor in my '50 Ford, I put a 2x4 under the oil pan and used a screw jack to hold the motor up while I took the bolt off the motor mounts so I could replace the water pumps.
https://static.speedwaymotors.com/pdf/910-18025.pdf
I think you can slide the old mounts out once unbolted."
Thank you for that link. Very much appreciated.