64 Bit Intel Assembly Language x86 Architecture YASM Syntax

I'm looking for an individual with experience in 64 bit Intel Assembly Language x86 Architecture to complete a project for personal use. The intent of the project is that the assembly code created will adhere to the exact specifications I provide, so prior experience in developing assembly code to precise specifications is important. Additionally, the project is time-sensitive and requires the assembly code to be completed as quickly as possible.