For an outside stove, I wouldn't worry too much about baffles. Adjust the flue and front air vents to adjust the heat.

For an inside heater, I would add a baffle just so the maximum use of the fuel is reached. Maybe weld some angle iron length wise, on both sides, toward the top of the barrel. Slide in a couple of pieces of heavier gauge steel. Use the two pieces to adjust the amount of baffle. Make sure they are removable for easy cleaning of the top inside of the barrel.

Reminds me, I have to buy a chimney brush tomorrow.