As it stands right now the best engine choice for half A is not really a half A and its no longer being produced or imported.
So that's why I've been spending my time looking at designing 1/2A models that fall between the great flying though really 3/4 or is it 5/8 A and 1/2A.
I've flown both the baby rm and the old top flite kits to death in my youth and the fell in the 144 sqin range. If the brodak.049 or a norvel.049 can work to pull between 180-200 square inches I'll be happy.
I'm not trying to redefine 1/2 A. Just trying to see if what's available is really viable.

My Green Giant (12 oz ?  32" span roughly 200 sq") flew like a scalded dog on an AP .061 and was stunt capable with a Norvel Big Mig .049. 



My Confederate Twin (18.2 oz 44" span roughly 286 sq") was one of the sweetest flying planes I've ever flown till some hoodlums got a hold of it.  Plane would fly easily on 1 engine although I never stunted it once it went down to 1 powerplant.  Again 2 AP .061's which really was too much power.  2 .049s would have been more than sufficient, but I would be concerned if one of the engines cut out.



My P51 (Miss April:  13 oz scale, can't remember the sq") Flew like CRAP.  Plenty of power with the AP .061, just never got it balanced right.  I doubt very seriously that and .049 would be able to keep it in the air, it was tough with an .061.  Put so much work in it I decided to hang it up in my boys playroom instead of destroying it by flying it.



The Lone Wolf (9.5 oz 32" span 190 sq") is an excellent flyer.  Even better now that I've dropped 1.5 oz of weight on the second one.  Again .061 for me, but a buddy flies an identical one with a Cox Golden Bee with no issues.



Best flyer to date:  the Mini Force built off pictures of the Sig  Primary Force.  9.16 oz 33" span 200 sq.  Again .061 Wasp.  I haven't put an .049 on it, but I feel certain it would fly well.  Plus there is still some room on it for weight reduction.




I guess what I'm getting at is a modern .049 has more than enough power to fly through just about any pattern assuming the plane is balanced and not overweight (under 13 oz maybe?).

Hey Steven, is that kit a Plastic Fantastic ?  I have one , it was a double kit, great flyer, but not much room to mount a tank. Built mine as a tank mount with Norvel .061 flies great , just not enough running time on those tank mounts. Would like to know if that is the same plane as i am interested in the 1/2a foam wing planes. Good luck , Ray