I was thinking award when I posted because I would split it between F in the outbound, and J or Y on the return.

But, upon further reflection, I don't think Asia miles let's you discount in this mixed class scenario. However, RT awards cost less than the sum of two one-way awards. In short, I suggest you study the award chart/rules a bit, and then you'll start to get a clearer picture of the best way to play it.