I ran in college and was extremely strong for my weight through out my experience. I entered college @ 155 pounds and left @ 160 pounds 6'0"and was always under 7.5% body fat on the pinch test. In high school my focus was on football with track to stay in shape. That being said, when I focused on track after my junior year (because at my weight I would have been limited to D2 or D3 football programs), I excelled. I was a state champ at 800 and regional champ at 1600 in high school and went to state in the 200, 400, 800 and 1600.
I ran 4 years at a competitive division 1 program and ran decent, although not national caliber times (unless I would have gone to a D2 or D3 school), and progressed fairly well over the years. There are pluses and minuses that come with the added muscle weight. The main benefit is you attract more girls (I dated a lot of the skinny runners "friends" that they never had the balls to ask out). And I think you tend to be a little bit tougher at the end of a race. The drawback is you have more weight to carry around the track.
Don't listen to the garbage about doing low reps (6 reps or less) as it tends to kill your joints in the long term and doesn't build strength as quickly as a little bit higher reps. I always did moderate reps (warm ups with 20 reps, and added weight to no less than 8 reps) and I saw my greatest progress strength wise and toning wise using that tactic. I never put on much weight due to the fact I was running 70-90 miles a week on average.
It is best to do super sets using complementary muscle groups (this was a tactic used by Michael Johnson that you can read about in his book and will shorten the amount of time you spend in the gym while still getting a good workout, which becomes invaluable when you are older) and allow 2 days of rest between muscle groups (you should hit each muscle group about 6 times a week doing this).
Looking back, I probably could have run a little faster had I limited the weight work and probably could have qualified for a NCAA regional championship (this did not exist in my day). I don't think I would have ever been a top national athlete (as I did not have the perfect physique and stride length), but I think that is probably a good thing, as I don't think I would have been as focused on my future career (it is a hell of a lot easier to make a living as a doctor or an engineer than it is as an aspiring professional runner working in a shoe store).
Whatever path you choose, the best of luck to you.