Take AP Physics 2 , if MIT is your goal, because you have to pass year of physics for any MIT degree.
If you can do some research in high school, on top of that, see if you can arrange that, but a strength in physics will help you a lot at MIT (and most engineering colleges)
because physics is a required course even for econ or CS at MIT.
Its better if the research work has a PhD scientist as the mentor, so it all depends on what you mean by “scientific research” class. If its a high school teacher, perhaps skip that. If its an activity at a local college, try to squeeze that in. But ask other students about the content and qualify of the “scientific research” class you mention.
Practice in physics problems is likely to prepare you better for freshman year at MIT.