Throttle stick takes care of this! DA85 or ZDZ 80 on a pitts weighs less than a 50cc with a cannister. Put a 24x12 3-blade on it and fly at lower throttle settings, you will have more power than you can imagine at a relatively quiet noise level. Most 26x10 props will turn in the low-to-mid 6k range, as would a 24x12 3-blade (high 5k for Biela, high 6k for Mejzlik or ZM). Of course, you probably don't want 10+ hp or 50# of thrust on an 18# plane.

The Brillelli is very good and very light. If noise is a consideration you need a better muffler (Scott's pitts muffler is nice and cheap). The MVVS/Evolution 58 is a fabulous engine but prefers a cannister or pipe which kicks up the weight to greater than the 80cc ZDZ or DA (on a muffler).

p.s It takes 30% more power to swing a JXF 24x8 at 6700 than a Mejz 23x8 at 6950. In fact, the 23x8 mejz needs to spin around 7600 rpm to match the thrust and power of the JXF 24x8 at 6700. That is why I am not impressed when people brag about their new 85cc engines (on "another" site) swinging a "huge 28x10 mejzlik" prop, because many smaller 26x10 wood props actually put a larger load on the engine.