Hi Matt,
I'd need to check the plans or the airplane to remember what I did with the stab. I think it was symmetrical but will let you know. At 1/4 scale if is difficult if not impossible to hide a 2 stroke cylinder 40cc or bigger inside a 1/4 scale straight 6 scale engine. Glen T. and I corresponded about options as he was interested in kitting a Pfalz DIII, but the engine compromises were too great (at the time). Some recommended an axial-reciprocating engine (bevel gear drive) - i don't remember the manufacturer. That would fit. Electric is a good option too. I didn't fly the airplane very much, mostly because of the set-up time at the field, so I don't have life data on the spinner. But it seems pretty tough. The molding technique eliminates excess resin and bubbles. I was careful to orient the composites symmetrically, and with lots of overlapping layers. Of course I balanced it carefully. However I don't make any promises - be careful, confident and comfortable with this kind of work or have one machined for you. As for inverted engines, I've never had any problems with my inverted DA or Fuji engines.
Seth