A 34 ACT is great, but keep in mind it's only part of the admissions process and determination. I personally know of a great kid who had a 35 ACT, all the leadership, Varsity sport, AP or dual enrollment with above a 4.0...great candidate who was turned down. He was basically told there just wasn't enough room for him in a super competitive district. He didn't need a Prep year to improve so it was just a turn down.
In the same admissions cycle my DS was a direct admit with an ACT closer to the "average" along with similar criteria above, but different congressional district. He was later told by an ALO that there were other candidates that looked better on paper, but his nomination interview is what sealed the deal and got him the primary nomination.
So I would encourage him to continue working on all parts of his package. You never know what score, essay, recommendation, or interview might make the biggest impact.