There's another reason to forget a magneto gas engine. In the case of the T-34, the cowl would require some serious and ugly surgery to accommodate a flywheel up front. I'm eventually going to build a 120 size Tiger Moth from NitroPlanes. I'm powering with a Ryobi 31 and it required conversion to CDI to deal with the cowl. With CDI, the entire engine will easily fit inside, with only the exhaust stacks coming out the bottom. With the flywheel, the cowl would have been a disaster.