Most likely very little to perhaps some original parts were used.
I wasn't able to find photos of P3717/DR348 when recovered, but here are some examples of other Hurricanes recovered from Russia.
Ex-Russian fighter to be restored at Rochester
Hawker Hurricane Recovered This Aircraft crashed into a lake near the city of Murmansk in 1942, it was found and[...]
Original source: Lend-Lease on airforce.ru
www.warrelics.eu