You'll be placing implant 5.0 * 10.0mm, and as the every osteotomy drill has additional 1.2mm tip at the end, you'll drill 1 step shoter drill in order not to perforate sinus membrane. so the drill size would be 4.5 * 8.5mm.

Secondly, bone density isn't that high at #15 position, so I suggested you undersized drilling in diameter. So it would be 4.0*8.5mm when it is normal (standard) offset which is 9mm.

Lastly, I have made the surgical guide with 12mm OFFSET due to thick soft tissue. In order to compensate the difference of 3mm, the final drill would be 4.0 * 11.5mm (Jennifer).