You would get a new MOS. An officer's MOS is determined at The Basic School (TBS) which occurs after OCS. What you did as an enlisted is irrelevant to what you do as an officer.
That said, IF you are in the top 10% of your TBS class, you will be in position to select MOS 0202 (Intell Officer) over those who are lower down in their TBS class. Even if you miss the top 10%, there is still an opportunity since TBS splits the class into three groups based on the TBS grade breakdown. MOSs still available after the top 10% pick theirs are offered to each of the other two groups in the sequence of the officer's TBS grade. What this means is, if you are in the top of the 2nd group and there is an intell officer MOS opening still left, you will get it. If not, you will have to focus on your 2nd and 3rd choices and hope one of those is still open. If not, it will be whatever is left over.
To some extent, your SPC (your TBS class commander) does have some input. If he/she determines that an officer's TBS performance is insufficient to indicate success at MOS school, they can supercede an officer's request for a specific MOS and force him/her to accept another on their MOS request list. Just the same, if they determine that an officer is highly qualified for a specific MOS and that officer wants it (e.g. MOS 0202) and there is an opening, they can help the officer to get it assigned even though he/she may not be in the top 10%.
Lieutenant Colonel, US Marine Corps-Retired
PS: Why do you want to join the Reserves and then go to college?? Recommend you reconsider if you have determined college is in your future. The weekend Reserve sessions are killers on college GPAs since you have very little to no time to study for any exams or complete labs/projects for the following week. If Final Exams are after a drill weekend, it is even worse. This was my personal experience. At that time, I was able to drop out of the Reserves and go PLC while in college on the GI Bill. If I did not, the chances of completing college was in doubt (I was in Aerospace Engineering).
Additionally, there is very little financial incentive for being in Reserves and going to college at same time. No tuition assistance or college paid for by being an enlisted Reservist. Pay for E-1/E-2 (Pvt/PFC) is about $200/month BEFORE taxes are deducted.