If peak power is developed at 18k that is not radical timing. I would call that peppy sport timing. Such an engine should have no trouble spinning a 9-7 APC up towards 17k and that will pull fine. A West .50 is a little higher timed yet, and will spin a 9-6 APC at 20k, which pulls hard on the ground and a pitch speed close to 120mph.

The major concern I have heard with heli engines, apart from shaft adapter issues, is that the 2-needle carbs are set up to run relatively rich through the midrange.