My "Aircraft of the Fighting Powers" gives the maximum range of the Bombay as 2230 miles, which agrees with your 3589km, so there's some consistency to start. the fuel load is given as 925 gallons, or 6785 lb. Assuming you trade 2000 lb fuel for bombs, then you are down to 70% fuel. Since you will use the same amount of fuel for takeoff and climb, I would think the range would be about 55% of its maximum, or 1975 km.
Hope this helps,
Ivor