You're right that ability to meet the specs is largely driven by the battery choice, but that the motor and battery decisions are related.
Two hours at 75 mph would be 150 miles - far beyond your range target of 85 miles - so I assume that you means for that to be two separate items:
- able to drive at 70 mph
- able to drive for at least 2 hours (will usually be driving at around 45 mph)