Have made a few of them in my time. From memory:
The X Wings working S Foils might cause him some problems.
I put Darth Vader's TIE Fighter together at a similar age myself without any problems.
The Snowspeeder went together fairly easily, but the cockpit could have been better.
The AT AT went together easily. Had a similar motive when I gave one to my friends Step Son when he was a similar age & he put it together with no problems. He was a Star Wars nut too at the time..
The Star Destroyer gave me some trouble when I put it together with gaps between the hull sections.