Hey @cgn626 - so imo schools fall into one of 3 broad categories - Grades/Scores not important, Grades/scores considered and Grades/scores important. For BFAs the last group is small. The first group contains most of the strict conservatories and some of the university based conservatories like CMU - it’s really all about your audition, talent, background and application. The second group is most of the rest of the universities with conservatory type programs - the audition/application matters most but they’d like you to have GPA/scores that keep you in the ballpark for the school. But each school’s “ballpark” range is different. Michigan and I think Penn State put it out on their websites what’s expected - fall below those limits and they won’t consider you. But the standards really aren’t that high, the GPA for U-Mich Drama was way below what’s usually required for admission to their other schools… it’s still mostly about the audition/talent/training. The third group is one where your GPA and scores will actually make a big difference in your chance of admission. That’s most of the auditioned BA programs, all of the non-audition programs and NYU. BU kind of falls in between groups 2 and 3 because your GPA matters but they tell you not to submit your scores if they are under the average scores for BU admitted students.
I’m sure people can chime in and tell you that certain schools that I’ve described in group 3 actually belong in group 2 - or vice versa - so take the above with a grain of salt - the schools will tell you plainly if grades matter.
I can tell you that my daughter had a 3.7 unweighted GPA and good test scores. She was accepted to most of the BA Drama programs she applied to and to NYU-Tisch as a BFA in their MT program. She was not accepted to Michigan or BU but we’re quite sure it wasn’t because of her grades! 
And boys have it a little easier than girls with MT applications. I would not let that 3.7 stop your son from applying ANYWHERE for a BFA. If he has the talent and can nail his audition, his GPA won’t eliminate him from any BFA programs I know of and only a few will even look at his SAT/ACT. That said - have him try hard to get a good test standardized score, it can only help and having a good BA backup school is important.