Hoping will not help you. Green will not either. You will need an op-up, but they are indeed rare. We talk about them all the time but in nearly 9 years as a CX Diamond, I'd say my long-term op-up rate across a massive # of flights, classes and routes is perhaps ~15-20%. If you're a Green I'd bet your rate is <5%. It varies based on the macro economy, which routes / flight times you frequent, and so many other factors. For example if you were to solely fly HKG-MNL in Y class as a DM, I'd say your op-up rate would be much higher. Even as a Green or SL I bet you could get regular op-ups on that route. Whereas if you're flying HKG-SFO in J on the daytime flight....which has no F....you will never get one (because F doesn't exist!) You get the point. It can vary massively.

To/from JFK, the op-up rate from PEY to J is reported on here to be quite good. That sounds like the best strategy to me: Buy PEY. Some posters have reported 30-50% op-ups rates on that route. Not to mention, you'll be accruing ~18k Asia Miles each round trip...so every 5 sectors you buy you can effectively upgrade 2 sectors. If you are really flying this heavily, you can have nearly guaranteed (provided you have a little schedule flexibility, to ensure availability) 40% in J class just buying PEY and upgrading to J. And the other 3/5 times I'd reckon you could score at least one op-up, especially because you'll be SL soon enough with that type of flying pattern. Does this make sense?

Unless you're willing to start at an outport (you can count on fares ex-TPE for say 3.5-4k USD), you will quickly blow your budget flying J and it's not sustainable. At the absolute cheapest I thought I once found a 5k USD fare ex-HKG to JFK, maybe? In reality the fares are more like 7-10k USD. I would pay for PEY if I were you.

Review this https://www.asiamiles.com/am/en/redeem/charts, and do some searching around here. Good luck.

Other resources are our FAQ (top, sticky thread in this forum) and this website which we maintain CX Fleet, Routes and Configuration Types. 77H is the 77W variant that serves JFK exclusively, while 77G is the 77W variant that serves EWR exclusively. The main differences are no F on 77G, but subtly I think 77H is better for op-ups because 77H has way more premium seats vs basic economy seats. So CX has more "wiggle room" if the premium PEY, J and F classes haven't sold. 77G has fewer premium seats.