You don't want and shouldn't have to clean the inside of the engine. Just simple strip and check for damage/wear. Don't use any solvents on a silicone filled crank either. Arguably when using good fresh fuel after run oil is not needed either! If I do decide to wash out an engine if a plug failed for example I use nitro fuel and allow it to evaporate leaving the oil behind.

All I do is check the engine for wear/damage and clean the exterior of the engine with brush/cleaning putty and if very dirty use brake cleaner. Make sure you have caps firmly installed on the carb, hsn fuel Nipple and exhaust port.

I store the engine in a plastic sandwich bag sealed with a silica gel bag inside. I have never suffered any corrosion or engine degradation in 20+ years of racing nitro and I don't use after run oil - it isn't needed.