I have a Venus 40 with an OS 46 AX. That is plenty of power for the Sportsman and maybe the Intermediate patterns. It doesn't quite have unlimited vertical, but the pattern schedules don't need that. I feel the Evo 60 will have much more power than usable and you will be better served to use your OS 50. It will also save you some weight, and will likely be easier to balance.

I also did not have wooden pushrods. Just wire ones running in a sleeve.

I built it per instructions and put the battery in the compartment under the fuel tank and it balanced just forward of the instructions 4-5/8". The plane flies great (have 25 flights so far) and I have had no issues with its handling or strength so far.

The Great Planes website has an addendum for the instructions. It had a change in the distance the thrust washer was from the firewall when installing the engine and a change in how to install the cowell.

Hope you have as much fun with it as I am.