From my own experience there are three perks to mounting an engine with it canted over. The first is aesthetic. Sometimes, especially on a scale model you just don't want the cylinder head sticking up above the nose. The second is mechanical convenience. Depending on the design canting the motor over may give better access to the fuel line or the needle valve. I've also done it to put the exhaust outlet where it will get the least amount of oil on the rest of the airplane. The third and likely most important in a sport plane, is bringing the carb closer to the center line of the fuel tank. Lowering the carb by rotating the engine will help with fuel draw, especially in a model where the thrust line is well above the fuel tank. In the case of the Kavalier it probably won't make that much difference. A semi-symmetrical wing such as the Kavalier is not as sensitive to down thrust as a flat bottom wing . The bottom line is that as long as the previous owner hasn't built in any misalignment you will probably be okay. If it turns out that the airplane does pull one direction or another with changes in throttle it isn't too hard to add a degree or two of thrust change by placing a thin shim between the engine mount and the firewall.