RE: ESM ZERO BUILD
The plane will almost certainly come out tail heavy. So a light weight engine is not needed or desirable. A heavier engine will not hurt. Also in your build keep all weight as far forward as possible including building mounts for you batteries and ignition module in the cowl as far forward as possible and keep everything in the tail as light as possible. You will probably still need to add nose weight but maybe not too much. Thats how it was on my 72" wingspan CMP Zero. However, it should be a great flying airplane.