Hey T Craft!
I used a 1100 mah pack right above the landing gear. I'm using a B&B smoke system so there isn't another battery pack- and the smoke tank fits under the regular tank.

I used blind nuts with 1/4 x 20 screws going through the engine and spacers to get the right clearance for the cowl. I didn't have to cut any holes in the cowl for the cyl head... just the muffler (B&B- stacks straight down) and the plug... but that's underneath and it needed cooling holes anyway. From the top and sides- you can't see the holes in the cowl.

You'll love her in the air!

Rick