Try the pervert damage test.
Create a custom arena and turn off kill shooter. Up your La7 on the runway and sit in it while a friend ups a jeep. Have him do one shot ping tests to see exactly what's happening while filming. Pervert did this with the Fw190 D9 to show the radiator damage modeling was pita. Do the same thing flying level with the friend on your six. He can use the Yak 9T and tap out single shots with the single .50 cal on the hood while you both film.
You might test MG151\20 single shots from a 109 or even from the Ki61 Ho-5. They have more arc than the hisso, ShVAK. Type 99, or Ho-5 are somewhere about the MG151.
Because of relative motion between your two planes in a 6 chase orientation. Your enemy is lobbing rounds in an arc ahead of your La7 for you to fly to. The damage modeling may favor rounds hitting in the front 1\4 of your fuselage while little to no damage to your woody posterior. A single 20mm would make a mess of the top two guns while protecting the engine if the initial damage modeled hit rational is the guns and support structures go first, engine second.
An offline static test would show you a damage count down list visa observation. Too bad you cannot enable shooting from gun position in bombers while on the ground. Then you could use an He111 to single shot test a 20mm after taxiing up and parking. The wirbel would be overkill. Or would it be possible to enable the La7 on a carrier and use a manned 20mm there in a custom arena with killshooter disabled?
