The OS 61 is rev happy and the exhaust my get in the way.I think its more suitable for a fast warbird or Pattern machine.
Wait for other opinions,but I think the 82 has my vote for all around power.It is content with a wide variety of props and nitro.You can experiment from there.I think the engines are similar in weight??
Perhaps a YS 63 will keep up with power and shed a few ounces?
If wanting to try any 3D the 4 stroke may help with low end thrust and fast spool up for stall recovery.If you havent purchased yet, the YS maybe a real consideration.Dont let the diplacement fool you,it will keep up with the bigger motors.