I've been looking for CFL stats on this, but haven't found anything.
In the NFL (2017), the best conversion percentage was 68.97% by Jacksonville.
The worst was 39.58% by Denver.
With the wider field and deeper endzone, I'd expect the CFL to have a high percentage but can't validate. But, I suppose the 3-down vs. 4-down offense could drastically sway this stat from one league to another.
Thanks - lots of good data here. It's close to the question... I was trying to see how many times the TC's made it into the Red Zone that resulted in a touchdown. This information shows how many times the Red Zone was penetrated and points were put on the board. But obviously, some is better than none!