I will always take a different approach. College pace.
Leave the cgpa/wcgpa out of the equation. There are over 2000 HSs in the nation. It is too subjective when it comes to posting the gpa, and sometimes even ranking.
USAFA is the only one that I know of that flat out says on their website 490 CR/24 E is deemed non-competitive. Now, with that info in hand and looking at the rankings from USNWR, Money, Fortune, etc. and always ranking behind USMA, I would say it is an uphill battle for you academically.
Key word academically. I didn't say appointment! Profs are not going to slow down the class like your HS teacher for you to catch up. It is up to you to get extra instruction.
SAT/ACT is national. It levels the playing field. It illustrates to admissions the academic foundation you have in your wheelhouse right now. I get test anxiety, but that only goes so far.
If you don't have the academic foundation now, you might be doing more harm than you realize.
For whatever reason you get an appointment. Come fall you will be in classes with many kids that were also accepted to Ivies. You are behind the 8 ball academically, and now you have the pressure of an SA lifestyle.
I know this is hard to read, but you might be better off going AROTC scholarship and applying next year. You will be able to get that academic foundation down while getting a taste of your future life. Plus a ROTC nomination.
I am sorry, but you asked chances, and if you were my child I would say:
What is your goal?
Commissioning or USMA?
If the answer is the latter, than I would say academically you need more time for USMA. 1000 SAT in VA is low, low, low. Safeties are 1200 on a good day.
~ It would be like being accepted to UVA (#2 Public Ivy) and attending there, plus the stress of military daily life where they control lights out and wake up. No...I will burn the midnight oil studying. Oh and at UVA, you can roll out of bed in shorts to go to class. Nobody is checking your room for cleanliness or if you shaved before class.
FWIW,
Just because they open it up, doesn't mean anything more than they opened it! You still need an MOC nomination. Last I knew, it was around 50% of candidates that get nominations, maybe less. From there you have a 50-50 chance.
~ I think it is statistically a 16% chance that you will get appointed.