I think the pain is the same with any size implant tbh but I hear that under the muscle recovery can be a bit more painful compared to over the muscle.
Thats a massive implant from a 34a.. I was offered 560 or 615 from a 34b and i picked 560 as i was advised by my surgeon with the largest implant i would be more likely to have rippling and stretch marks, so make sure you check that those arent a risk hun x