Starch, with 6.7x5.5”, undergoing length surgery is a bad choice. And the reasons are the following. You are slightly above the average now. Surgery can increase the length of your unit as well as decrease it. Now, probably with the surgery your increase will be 1” at best (I say this because you already did some serious lig stretching). The same gain may be achieved with natural PE. Surgery won’t provide you with anything enormous that is worth taking risk for. On the other hand there is a reality that your length will decrease, putting you in an under average category. Do you really want this?
Good candidates for surgery are people on the tails of length distribution - the ones who can afford to loose some and the ones for whom a length increase will add so much benefit that it will outweigh the risks of possible length loss (I am talking bordering micropenis condition here).