Vince, you're looking at the wrong curve. Don't look at the efficiency curve, look at the power absorption curve. It goes as the cube of the RPM with minor variations for airspeed and propeller efficiency. (Reference: Fraas' "Aircraft Power Plants", McGraw-Hill 1943, page 88.) So, at full power (not full throttle like on the Lycoming, but at full power) the prop rpm will be very close to its design ("max cruise") rpm even at zero airspeed. (The prop rpm will be a little less than cruise rpm because the prop efficiency is so bad at zero/low airspeeds.)

Then the CVT will allow the engine to spin up to its rated rpm in order to deliver its full power to that prop from brake release all the way up to full-power design airspeed for the prop (and airframe!). However, be careful in your choice of CVT so that you get a range of ratios that will limit the propeller's rpm. You'll want a CVT that is at minimum reduction ratio when you get to cruise airspeed so that your CVT will not allow the prop to overspeed when you glide. Also be sure to use both an engine tachometer and a propeller tachometer, since propellers have operating limits, too.

I think you'll have success with this if you choose components that are matched in terms of horsepower and rpm and put them on an airframe that is matched to the design airspeed of the prop and the horsepower. (I shouldn't have to say that but so many good projects have gone astray on those "details"....) Might I suggest a Cub or Champ as a good place to start when you get tired of the "sled." And try to get an engine/CVT combo that will allow you to use the Cub's same prop for good comparison testing. However, I think that, given the same horsepower as the engine you're replacing, the only advantages you'll see are shorter takeoffs and modestly improved climb. (OH! And a cheaper engine package, too?)

I can't wait to hear a progress report!