I've used Allen Tailors multiple times with good results - 150 Allen St. Never anything as complicated as what you're looking to do but they came to me highly recommended by some other SF members I respect.
Another option I can't vouch for personally that people do mention quite a bit tho is Dashnor Tailoring, 320 E 81st St. Apparently he's the tailor where all Tom Ford alterations are performed.
Appreciate it! Thank you