-There have been musky cought in the st. Laurence with enough length but not girth.
-There have been musky cought in Lake Erie with enough girth but not lenght.
-Georgian bay seems to be somewere in the middle, and has coughed up 2 legitimate fish over 60lbs.
-With global warming increasing the growth rate of warmwater species in northern climates, I think some of the large canadian shield lakes have a chance too.
I think any one of these could do it, but if I were to put my money on one, it would be georgian bay.