Thanks for the responses. They are what I expected. He is He will keep working at OF as well. He's 6' 2" (likely that is all he will grow) and right-handed. Some power.
It is just interesting that his HS coach clearly sees more value in defense at 1B than at the corner outfield spots. He will put much slower guys in the OF spots and keep my faster son at 1B.
It makes some sense to me in that 1B likely has multiple plays a game where defense matters (either in bounced throws, quick throws to other bases, fielding grounders). My son gets to little foul pops in front of the 1B dugout or down the RF line that other 1Bs wouldn't get to.
A right-fielder my only have 1 or 2 plays a game where speed matters.
Just trying to challenge the conventional wisdom . . .
Don't forget that the quality of throws to first improves as you move up. So 1B becomes easier. Depending on the HS, you may need a defensive beast at 1B just to get an out. Good luck.