Rewalsar to Dharamsala is 154 km approx.
I started solo from Rewalsar by Royal Enfield Thunderbird Twinspark motorbike via National Highway 20 reached Dharamsala in 5 hours 30 minutes. It was rainy season and few places there were landslides. Maybe if no rains 5 hours will be the total journey hours.
Rewalsar to Manali is 135 km approx.