Depending on how long you have been doing six runs per week at 35-40 miles you might have enough of a base for a 5K.
You have about four months of good training time until your race – correct?
Does the 5K course have hills? If so then you'll need a good deal of hill training.
Form drills like strides help improve your leg turnover ratio. Intervals are good but they shouldn't be your only speed training. I know most people feel 800's are overrated but they really helped me improve and nail down a good half marathon.
I would mix in form drills and a small amount of hill work along with the intervals. Also, fartlek (speed play) is something I like to use near the end of a run when I am good and tired – it helps build mental toughness as well as knowing what it feels like to push when the legs are spent.