Use steamengine like he said. I'd probably say 26 or 28g wire, Kanthal is always good to start with but if he wants to do TC in the future SS/Ti/Ni is available.
Note that Steamengine is not perfect but gets you close, the deviation becomes more noticeable at higher resistance. So where steamengine may say 11 wraps for something you might need 13 in reality, or so my experience with higher ohm builds has been.
As far as builds, it's really going to depend on the tank he gets. If he's looking for a tighter draw MTL vape the Goblin Mini is something people seem to like. If he goes DL there's tons of options with different styles and sizes of decks. Those differences will change what you build. For example if it's a dual coil setup you'd have to make 2 3Ω coils because parallel setups split the resistance, so stick away from those for higher ohm builds.
Just lots of little things to pay attention to but Steam-Engine is the tool you want to be using, and likely 26 or 28g Kanthal to start for higher ohm builds.