Hey buddy, awesome you're building that SIG Kadet 51-it's a fantastic trainer!

For the electric conversion, definitely go brushless. A good setup is a 3542-900KV or 3548-1050KV motor (around 600-800W peak) paired with a 50-60A ESC and a 5000-6000mAh 3S LiPo. That gives you power similar to a .35-.46 glow engine, plenty for aerobatics, and easy 30+ minute flights at cruise throttle.

Balance is key since electric is lighter up front-mount the battery forward or add a bit of nose weight. Do a test glide first to check CG.

Happy building and flying! If you need more details on props, wiring, or anything else, just ask. You've got this!