That equipment sounds great.
When I was in college, I used to work at a tennis pro shop lead by a former pro. I asked him what it was like to play against pros I'd seen on TV. He said, "Imagine the very hardest shot you've ever successfully hit into the court. The pros do that with
every stroke."
That's sort of what it's like for international races. At age 17, he's racing with guys as fast as the big dogs. And the pace of the rest laps are faster than the sprint laps at some tracks.
Hopefully your son can settle on a fit and get enough track time (at speed) to feel comfortable at Worlds and further.
Also, don't forget Shimano SPD-SL pedals. The normal pedals can be tightened very snugly. A couple of years ago I had Ultegra, Dura-Ace, KEO and LOOK MAX 2 pedals and I found that the maximum exit tension setting on the LOOK pedals was equivalent to maybe 25% of what I could set on the Shimano pedals. So, if you want tight pedals, go with any of the Shimano SPD-SL variants. I really like 0-float cleats for a very "attached" feeling with the bike. This was recommended to me by a to US coach (Olympic medalist) that coached me at the time. Even for enduros. Even Cav used to ride them:
