You may not like my answer.
This is from experience with my son. In HS he was 6'3" 230lb 1st baseman. What he had to sell was as a hitter. He was a good/serviceable 1B, with 60 times the same as your son. He played on a good HS program and did a good amount of events for exposure.
What we found was that in spite of good numbers as a hitter, he got very little attention (one showcase he had a HR and 2 2b's and only got an invite to a camp). After a while, I made a point of talking to several prominent scouts and recruiters. What I learned is players like my son were recruited on an "as needed basis." Those that I spoke to made it clear that coaches could always move a player from the outfield, use a catcher or another infielder rather than focusing on a player that could only play 1b.
To overcome this we started focusing on programs where there was likely a need; even though they may not be recruiting for the position. This meant looking at rosters and stats for teams. We looked for teams where the incumbent 1b was a senior or junior. We then looked a the depth of underclassman and checked stats to see how they had performed the freshman or sophomore year. We also looked at their physical attributes; if there were one or two other 6'3" LH 1B that were freshman or sophomores there was a higher likelihood that the coaches felt that there needs were being met. We also looked at depth at catcher. If they had several good hitting catchers we knew that the competition would be greater.
In the end, he found 3 good schools that wanted him. A D3 in Ohio, a D1 in South Carolina and a D3 in Texas.
The key was we did not wait for the schools to come to us. He went out and found schools where there was likely a need and then "baited the hook" so that the schools would come after him.