absolutely get a LOR from this professor. you don't have to ask for it now, do you? you're the #1 scorer in his class. trust me, even if you don't know him, he knows you! go talk to him. are you interested in biology? that helps even more!
i'll give you two examples to back up my statement. a very good friend of mine scored top in a biology class of 210 premeds. she never went to a single office hour. when she set up an appointment to talk to the prof the following semester, he had already asked OTHER professors about her, and was super friendly to her, and became an invaluable advisor to her for the rest of her days in college. she will be going to ucsf this fall.
don't like those 'my friend' stories? fine. I'll give you a personal story. I scored in the top 5 in a 150 people premed chem class. I didn't go talk to the professor much myself during the semester, but after we got our grades (at the persuasion of aforementioned friend), I went to go talk to him. I ended up working in his lab for two years, and he ended up writing the strongest letter of recommendation for me. Almost at every school I interviewed, at least one of my interviewers commented about the strength of his letter. (I was a little bewildered. He's a big name prof, and after I started working in his lab, I never saw him again, lol.)
the point is, it is a GREAT accomplishment to score 1st out of a class of premeds. take that, and use it as a great way to get to know professors! in general, they love smart, up and coming young people, and you'll get to have a wonderful supporter during not only your college years, but throughout your medical school application process and beyond!
goodluck!