Maybe. Depends on how slow you start. How good you are about taking in nutrition and fluids while running 7 hours. If you have done enough long runs to not be walking at 30 miles in. Would you run a marathon on 5k training? A majority of people could do it if they slowed down enough.
Most people start too fast and don’t eat and drink enough. That 2:20 marathon isn’t helpful if you walk the entire second half.