I would like to explain you are confusing the process. Adjusting status is what you do inside the US. Which is why members are saying it is fraud to enter with that intent.
What you want to do and want to ask is how to petition him for a visa either the K1 fiancé or a CR1 spouse in his situation.
I'm sorry I can't help with it more. But I wanted to clear things up so when you are ready to ask more questions no one will be confused.