I'm having a breast lift with implants, would 415cc implants be the right size for me? (Photos)

Thank you for the question.  Hard to predict if you will experience any breast size change with a 7 pound weight loss (if so, who will likely be minimally noticeable); nevertheless, you are wise in achieving your long-term stable weight prior to proceeding. Based on your photographs, demonstrating significant breast ptosis, you seem to be an excellent candidate for breast augmentation/lifting surgery; in my practice, I would at least consider a two-stage process. During the first operation, a breast lift would be performed: during the second operation the breast augmentation procedure would be carried out.
 Generally speaking, patients undergoing the breast augmentation/lifting combination operation should understand that it is significantly more complex than breast augmentation surgery only and that it is associated with a significantly higher risk of complications and need for additional surgery ( compared to complications and need for additional surgery when patients undergo either one of the operation separately). 
Also, patients undergoing the combination breast augmentation/lifting surgery should understand that there are limits as to how large of an outcome can be achieved, given that breast lifting surgery does involve breast skin removal. On the one hand, breast augmentation surgery is expanding the breast skin “envelope” while breast lifting is (by definition) tightening up the breast skin envelope. These 2 forces are counteracting each other. 
Therefore, it becomes important to remove the appropriate amount of breast skin and to use the appropriate size/profile of breast implants to balance these 2 forces appropriately and to allow for achievement of the patient's goals while minimizing risks of complications. 
In my practice, "tailor tacking" is an important part of the mastopexy and mastopexy/augmentation procedure. It involves TEMPORARY  closure of the skin (for example with temporary skin staples)  to double check the amount of skin that is to be excised during the procedure. This maneuver is done to ensure that enough skin, but not too much, is removed. On the one hand, it is important that enough skin be removed to achieve the aesthetic breast lifting results the patient is looking for; on the other hand, is important not to move too much skin creating tension upon closure and potential wide scars.
The tailor tacking technique is very important when performing breast augmentation/mastopexy procedures. Again, this technique allows for a double check of the skin excision prior to the actual excision being carried out. In this procedure (breast augmentation/mastopexy)  if too much skin is removed it will limit the size of implant that can be used and/or the surgeon may experience tension upon  closure of the skin resulting in  wide scars, wounds healing problems, and/or implant exposure.
Also, generally speaking, the best online advice I can give to ladies who are considering breast augmentation/lifting surgery (regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work. 
2. Again, have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining which operation and/or breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "C or D cup" etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate. The use of computer imaging may be very helpful during this communication phase.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery. The use of temporary intraoperative sizers with the patient in the upright position makes selection of the best breast implant size/profile relatively easy.
Best wishes.

Implant sizes are determined by a comprehensive, detailed examination of your chest wall measurements, your tissue quality, and your desired look. The best way to find out which volume would suit you best is to try on sizers in the clinic. You also will benefit greatly from the lift, as it will further improve the appearance of your breasts and make them fuller, especially on the upper poles. Losing weight may have an effect on your breast tissues, but usually, it does not have any significant volume loss.