My son had a very similar issue. He was a low 70's rhp late in his sophomore year.
He went to throwing experts: Texas Baseball Ranch, AZ Baseball Ranch, and 212 Athlete to overcome his throwing issues, and develop a throw-training program that he could continue to work on. In 16 months his velo increased 12-14 mph.
This is where I would put your money. Build the velo, then build the relationships one-by-one with the college coaches, at the schools that he is interested in.
He attended Headfirst and Stanford camps - both are excellent. But different. My son met more coaches at Headfirst but had better one-on-one relationships from Stanford.
Perhaps you can have him work hard with one of those programs now in the early summer - then have him attend Headfirst or Stanford later this summer. Don't forget the Top96 Academic West - much less expensive, and reaches a fair number of colleges that you have mentioned.