Hello, and welcome to the forum.
My son did not attempt a Headfirst camp, but did go to several PG events, as well as a few other academic showcase type camps.
It helped for us to see how he did, and get feedback from the coaches.
While the showcase type camps helped to spark some interest, I think going to PG events was important from a self promotion standpoint. While getting a PG rating is not mandatory, it didn't hurt when letting coaches know how a respected organization evaluated him.
Additionally, velo results(or other evaluated skill sets like pop times) are posted on their website, and coaches know they are accurate.
As to specific camps, after we got an idea of which colleges might be interested, we visited a camp and sure enough he was made an offer. So unless your son stood out as a stud during a showcase, you will need to have him do some self promotion, pick targeted schools, and consider going to their camps to have a better chance.