Not me. For a kit that size I'd go gasoline for certain They are MUCH cheaper to run and are easy to tune and maintain. Don't know what a four-stroke glow of multiple cylinders takes to keep happy.

Problem with smaller radials is that you need multiples of the peripherals - which add weight - so five .25 cylinders might give you the displacement of one 1.25 size single cylinder but you will have a penalty in weight to get airborne. But, as CastleBravo noted - you'll likely need nose weight of one kind or another, anyway. You may come up with something like an Evolution seven cylinder 4-stroke glow that will give a good sound and have plenty of power for a 30 lb model. A glow engine won't sound or behave like a supercharged Nakajima Sakea 14 cylinder no matter what you do. Anything "model size will have higher rpm and fewer cylinders. The 1,130 Hp version took off at 2,200 rpm. Compare that to about 6,000 rpm for a small multi-cylinder four stroke.

http://pwencycl.kgbudge.com/S/a/Saka...aft_engine.htm

http://www.horizonhobby.com/7-cylind...engine-evoe777

You want a speed of 65 mph to be "scale" to the top speed of a Zero. That's pretty zippy. But they didn't maneuver so well flat out and were harsh to control; so probably 275/5 = 55 mph.

A one cylinder glow is just as radial as a seven. It's just that it has fewer cylinders. ;-)