Dick, thank you very much for this spot-on explanation! I've never seen one that short and clear. I only used the terms cubic and quad wing loading without explaining them. May I add that "fourth power scaling" gives not only scale speed but also scale motion (acceleration, roll rate, etc.).

Sorry, again I have different figures, mainly only 25,000 lbs weight for the original, leading to lower weights and wing loadings of the model as well. But incidentally spalex chose a target weight that comes very close to your "three point five power scaling" even at the lower weight.

This similitude mechanics, as well as electric drive layout, are two of my special interests in this hobby. (The third being testing different airplane/drive layouts in a simulator, as Evan did in reality.) So even if nobody cares, only for my pleasure:

The 4.5 lbs weight for the 1:12 scale model, giving slightly more than 10 oz/sqft wing loading, will make it like a park flyer. The original determines it to be a calm and slow park flyer (as opposed to an aerobatic one). So expect about 20 mph cruise speed, only low wind capability, and easy landings provided the tip-stall problem is solved.

As to the drive I should have been more precise. On second thought I'd recommend a higher-pitch propeller after all. Reason is that the model will need quite little power in cruise flight, what should be most of the time. For take-off and climb much more power is needed, and the motors have to be chosen to deliver it. But they can still be quite small when overloaded during the short time of take-off and climb, say one minute maximum. After that, cruise power (and current) is typically only one third of climb power. You can afford to waste some energy during the short climb, but not during the long cruise. So the props should work with best efficiency at low power (1/3) and rpm (1/2), requiring not much diameter but some pitch. That's the basic idea.

Assuming you'll use common outrunner motors and standard LiPo batteries, I have some matching drive layouts with 22xx motors. For a very scale-like climb (and take-off only from paved runways), a 2208/34 motor, 2s2200 LiPo battery, and 9x6 APC SlowFly prop would suffice. One such drive gives 0.83 lbs static thrust (6 A current draw), 50 mph top speed (!), but will work with maximum efficiency (45% total) at 20 mph or less with 2.0 to 2.5 A draw. The static thrust/weight ratio 0.37 will just suffice, but one complete drive weighs only 6.5 oz. Two weigh 13 oz, of course, what is only 18% of the total weight of the model. (Who would have thought a few years ago.)

Safer flying would be easier with the bigger 2212 motors. A 2212/34 with 3s2200 battery and 9x6 SF propeller gives 1.12 lbs static thrust, meaning 0.5 T/W ratio what is more than enough. Same speeds, same efficiency. Weight is 8.5 oz each, 17 oz both, 23.6% of AUW. Climb 7 A, cruise 1.5 A. With this drive, my parkflyer (same wing loading) cruise-flies up to one hour (demonstrated), but I use it for thermalling.

If you want to use scale-like props you'd need three-bladers with 11.75" diameter, which are far too big for this drive layout. But if you find a 12x7x3 with narrow blades you should be fine. With a 2s LiPo, the 2212/34 would give .38 T/W and a 2212/26 about 0.54 T/W. Weight would be 3.5 oz less (total). Current draw, rpm, and efficiency are different but still similar. Endurance is less but still more than you'll need.

Another idea is to build the model still with flaps, despite the low wing loading. The split flaps are small and simple, anyway. You'd not really need them but they might be handy. Forget the wee bit more lift, but the drag lets you control the landing approach, and the effectively increased decalage makes the model stable and easier to control (in calm weather, anyway) and should avoid the tip stall in landing configuration (take-off as well). The wing would be efficient in "clean" configuration, and "dirty" the washout would be achieved by increasing the inner wing aoa instead of reducing the outer wing aoa.