What a surgeon leaves is as important as what is removed.

Becky, please be explicit with your surgeon.  Your insurance company may have a weight requirement (gm/side), which your surgeon will discuss with you.  It seems that you will meet the height/weight guidelines for most insurance company sponsorship, however we all accept that bra size varies with manufacturer.  If you have been busty all your life, reduction to a B may be too much of a body image shift.  Depending on the technique used and the composition of the breast, you would be well served by taking enough to remedy your musculoskeletal symptoms but leaving enough to keep you happy.  Remember that glandular tissue weighs more than fat, so if you have been told that your breasts are dense, you will probably tolerate 500gm/side, without any problems.  Chat with him/her before the surgery.  Good luck.