Originally Posted by
gregL
Are his feet done growing? Generally expert level skiers with a 27-ish length size down to 26.5, but there's no rule he has to - a 27.5 would definitely help with "all day comfort," and give him room to grow. He should probably stick with a medium volume last rather than narrow, but this depends on who his bootfitter will be and what sort of performance he's looking for vs. what level of comfort he needs to patrol all day.
His main issue will be instep height; he's well above average for a 27 foot (67mm - 72mm) so a heat moldable boot with a tallish instep that can be made taller with heat molding (thinking Atomic Hawx Prime) or a 3-piece shell with an open instep (think Dalbello Cabrio MV). Some bootboard grinding may also be in order. I can't really recommend a flex without his height and weight.
Morton's issues are usually addressed when building the footbed, either by depressing the area under the metatarsal ridge and/or adding a bump to widen the space between the 2nd and 3rd mets when weighted, but again it's a job for an experienced bootfitter.
Hope that helps, but there's a limit to what I can tell you without seeing his feet.