Can anyone show me what a 650cc, moderate plus, under muscle would look like?

There are different computer simulating programs to assess the best breast size when you sent your pictures. However none of these programs are better than a experienced surgeon's eyes. First of all how do you know that you need a huge implant? Do you have breast ptosis (dropping)? What are the exact sizes of your breasts? Big breast does not mean a beautiful breast. A beautiful breast should be in harmony with your torso and should have a good conical projection with upper fullness and correct nipple position. So it is better to leave the decision about your breasts to your board certified plastic reconstructive and aesthetic surgeon. Good luck.

In my practice, I use Crisalix 3D simulation with which you can see what size of
implant would suit you and how you would look post the surgery. So depending
upon whether you choose 280 cc, 350 cc, 650 cc or whatever size you choose, you
can see how it would look on your body. I would recommend you go for 3D
simulation; patients really appreciate that.