I'm assuming this guy is labeled 127mm because it's for a 127mm lens?
Correct.
Years ago I developed a procedure for making a cam from scratch for the Super Graphic
https://graflex.org/helpboard/viewtopic.php?t=4653
Lens are rarely their marked focal length, they can be ,1mm to 3mm either side of the marked focal length. The greater the difference in actual focal length of the lens and the cam in use the greater the error at distances. A .1mm difference will be off at 3 or 4 feet while a 3mm or more difference will be noticed at 10 feet or more.
Find a 127mm lens, common, should be around $100 in working shutter, focus the lens at 100ft, 50ft, 25ft, 15ft, 10ft, 8ft, 6, and each foot closer until the cam travel is reached measuring the cam height at each distance, calculate the ratio of bed travel to cam movement.
Take the new lens and set to infinity with the RF at infinity then how far the rails have to move to achieve the same distance focus as measured until the travel of the cam has been reached in forward rail movement.
Cut a piece of aluminum or brass the same length and thickness as the factory cam, infinity height on the right, the focused distances height moving to the left using the travel ratio to determine the exact position then test against the lens.
You should now have a cam that matches the lens if all measurements were correct. The factory cam is nickel plated brass. I think the hole is for weight reduction but may be for ease of removal but not absolutely necessary.