lets please discuss the rules here so its all in one place 
you said:
I think methods of length 75 are already too long and I would hope that going forward we can get contributors to write smaller methods. So therefore I would suggest we keep the rule configured as is so new methods that are added are smaller. If PRs touch existing methods the reviewer can simply ignore this codacy comment and merge anyway. But this still helps in driving contributors to think about refactoring and write code that will be maintainable in the long run.
Also I checked on codacy filtering Checkstyle MethodLength and found ~60 methods over 75 lines which I think we’ll manage to shrink over time. There are exceptional methods with > 400 which is simply horrifying.
What number would you see as acceptable?