A warbird with less span than 12meters (39.4') must be flown with a .15 over here. (Aces rule)
construction is either balsa(light,strong and explodes on impact), foam (resilient but not durable), or as I do, a combination of both which is very strong, lasts forever and impact resistant if clad with wet paper and waterbased floor board polyurethane. Weight is typically less than 900 grams (32oz). No decalco's needed, because all can be printed on the paper that is used for finishing. The urethane paint is very fuel resistant.

For brute power without weight penalty in a .20 sized housing, and disregarding rules, there is no engine that can beat the .28 MVVS with black mousse can type muffler, unless you want to pay double or up to quadruple prices for racing class engines.
Mortality rate (half-life time) is quite high in Combat, so I would not use my super class engines for that. Prime considerations are quick starting (first dab of starter), quick power-up and high crash resistance with low cost small parts.