It is more important to discuss the "look" you want with your plastic surgeon rather than to get fixated on a volume amount. If you want significant upper pole fullness far beyond what is "natural," then go with the high profile implant. Based on your width, the moderate profile implant would be in the 275-300 range and wouldn't create upper pole buldging at all. This is what "natural" would look like. The moderate plus profile would create some excess fullness but not excessively. So decide on the implant based on the "look" you desire and using the right base width, the volume just follows. Don't lock in on a volume number.
The implant shouldn't move laterally if the submuscular pocket is created properly and if you don't do excessive pectoralis muscle exercises for 8-12 weeks after surgery which could cause the muscle to pull the implant laterally and superiorly before the pocket is fully lined with a capsule.
