ORIGINAL: mcarleno
I think the only issue on this plane with horizontal mount is that if you are using a sport muffler your probably going to have to make some mods to the firewall. Inverted engines work fine but you may need to make adjustments to the tank position. If I remember, the tank is already pretty tight and rides above the nose wheel bracket. I don't think my Dad modified the tank location. When filled, and not running, it does drip a little through the carb. He has not had any prolonged inverted flights so I don't know if it would be an issue. If you go inverted, make sure that you store with the engine head up or you will fowel the plug.
My preferred arrangement is side-mounted. See my avatar. But the muffler would strike the firewall in this case and probably get in the way of the wing too. That's why I'm thinking (almost) inverted.
Thanks for the tip on storage and fuel fouling the plug. I hadn't thought of that.
Another option would be to just mount the engine upright as per the plans, then use a Jett or Tetra bladder tank. That way minimal foam insulation would be necessary (fuel foaming isn't an issue) and it could be pushed higher into the tank cavity.
Thanks for the reply!