600 or 800 Cc's over or Under the Muscle? Will These Achieve my Goal? Thank You (photo)

I would suggest putting the implant under the muscle.  I also would not necessarily focus on cc's but rather on BWD and profile.  I would suggest you use an Allergan style 45 gel implant. This will give you a full round look.  If you go to a saline implant  to get more cc's you will get more distortion than you want.

It sounds like being made too large is not going to be a problem.  I don't use implants that large but it sounds like you want to go with the larger size, and I say, God bless you, go with the 800!

It's good you clarified that you want a "full round porn-star" look, rather than a natural look, since they are two very different looks. It's also good you show pictures of your desired look, because the breasts in those photos are larger than a DD cup.  Saline implants in the 600-800 cc range will accomplish your goal in terms of size, but I would caution you against it. Generally speaking, the larger the implants, the larger the problems. In addition to the usual risks of capsular contracture and implant rupture or leak, 800 cc implants will place a lot of stretch on your skin, and you can get stretch marks on the breasts, along with premature drooping. They will also put pressure on what breast tissue you have, and distort your natural inframammary fold, because the volume has to go somewhere, and there is only so much room to go up and in (before you get uni-boob). Obviously we all have different preferences, and you can always find a surgeon who will do this for you. I recommend only having this type of surgery done by a board certified plastic surgeon. Just know what you're getting yourself into before you start, and plan your budget for the possibility of additional surgery.