Hi!
Problem with larger tanks is that the engine cannot cope with the changing pressure that occurs from full tank to nearly empty! Our engines go leaner as the tank empties. You probably know this already. This problem with the engine going leaner and leaner as the tank empties is worsened the larger the tank is.

To remedy this lean out tendency it is vital not to use a too large tank and to use two clunks (Uni-flow system)in the tank for more even pressure distribution to the carb.
But...a 300cc ( 10oz) will probably work okay too. But I would still recommend a 240cc (8oz) tank. On this tank you can fly for nearly 15minutes.