Hi Mom2,
Welcome to the site. Others will chime in with better specifics regarding the two options. I just want to point out a few things to help you utilize this resource to the fullest.
Continued direct questions are encouraged. You can also search threads here by topic, certainly including Texas Baseball Ranch and Driveline. They are both reputable and there are many related threads you can browse.
Most D3's recruiting timeline is heavy on summer between junior and senior year and often a bit later. So, for that level (as well as most JC and NAIA) your plan is a good one. It also matches his current measurables, based solely on the throwing velo you mention.
Assuming your son's local pitching instructor is experienced, reputable and current, you will also want to bounce the options off him as to avoid any conflicting philosophies or mechanic teaches - and maybe he has some specific insight into either or both.
If your son is on the typical maturation curve, a lot of progress can happen over the next 6-12 months, much of it just from the natural growth process, which you cannot rush.