Chicken plucker finger size?

[Sampsonbee]

Hi, I'm building a whizbang style plucker and have a question about what size fingers to use. It's main use will be for meat bird processing. I have some 2.5inch fingers but they seem really small. I feel like they should be more like 3inch. I have time to order the right size...but what size is that?
Been keeping and processing chickens for over 25yrs, usually borrow a plucker or bring to abbitor, but abbitor is out of business.
Thanks in advance for any help

 

[iwltfum]

any plucker I've owned uses 3 5/8" fingers with 3/4" hole.