A warbird will not make a good 3D platform. They are fairly fast and thus have smaller ailerons and much less elevator throw than a 3D machine. If flutter is not an issue, they can be flown fast and most are reasonable regarding drag.

The issue to be concerned about is loading... too much engine weight can be a problem as they are generally heavily loaded to start with. A glow designed plane might tolerate a light gasser but not a heavier bigger engine.