Consider transferring 220k from RBC Rewards to Asia Miles which would bring your AM total to 255k. This would get you 3 x one-way business class on Cathay (85k each). For the return in business you can use Aeroplan. This way you will have points remaining in both programs afterwards and you get to try different airlines/products. RBC occasionally runs transfer bonuses to Asia Miles which would allow you to transfer even fewer points but I have not seen a bonus promotion the last couple of years.

Also, this goes without saying but make sure there is award availability on Cathay before transferring any points.