40:1 should do you fine.
Keep in mind that when you change that ratio, you are affecting your fuel (A/F) mixture, too. Less oil, more gas..richer.
I've read some tech articles that have dyno charts to prove that 2-stroke engines make more power with more oil. As long as they could keep the plug from fouling, the HP output of the motor continued to increase as they increased (lowered the numbers) the ratio.
Of course, that didn't have anything to do with carbon buildup after a season ride.
What did that have to do with anything?....uh............
dunno