You probably should aim something like 69-71 laps, although it depends. Faster (more like 400/800 type) 2 lappers usually have a bigger difference between splits, and vice versa.
Here´s a general example of a base phase that I think should suit to you. Mileage at the level that you can handle, training should be repeatable and progressive. If you start from the top you risk your health and lose the room for a safe progression. If you go through something like this for months you can be sure that you have a strong base and basic speed-anaerobic capacity. The sprints could be short hills in one week, or a combo of short hill and flat ground sprints for basic speed, and the 150´s are done more relaxed for anaerobic capacity which also can be mixed with the short stuff or done separately. Progression in these too and not too much in a single workout (5-8x short sprints / 4-6x150m is plenty).
WEEK 1
M Rest / easy run / cross training
Tue Drills + ~50-150m sprints (can use hills/mixed) /~3-5´rec, circuits/weights. Easy run
W Progression run / LT workout / Tempo run. + Optional easy run
Thu Easy run / medium long run / doubles
F Easy run/rest (circuits/weights)
Sat 800m-1600m workout, can use hills. No longer than 200m / ~30s @ 800m or 300m / ~45s @ mile pace/effort. Jog rec (1:3/1:2). Can include LT work. + Optional easy run
Sun Long run
WEEK(s) 2 (+3)
M Rest / easy run / cross training
Tue Drills, ~50-150m sprints (can use hills/mixed) /~3-5´rec, circuits/weights. Easy run
W Progression run / LT workout / Tempo run. + Optional easy run
Thu Easy run / medium long run / doubles
F Easy run/rest (circuits/weights)
Sat 10k-3k workout (+ 3-5x200 @ 800-mile pace). Can include LT work. + Optional easy run
Sun Long run
Every 3-4th week mileage around ~70-75% of normal, include rest day(s).
Increase the mileage/intensity after ~6-8 weeks and stay there ~6-8 weeks until increasing again. ENJOY