Orientation is not as big a factor as is surface area. It was once believed that color played a significant part. Black was said to dissipate more heat. So a bunch of people painted engines black. Well Black absorbs IR nad UV better than light or reflective colors,and that leads to an object heating up more and quicker but that hardly applies to the heat generated by the engine. What they did was actually make the engine run hotter because the paint added a insulating factor. Utlimately it is the number and size of the cooling fins. Expose as much material to the cooler surrounding air as possible. A rough sand blasted bare metal finish is better than a smooth highly polished one (The tiny pits in the surface adds surface area) Small holes drilled into the fins (so long as you do not remove more surface area than you add) also helps, noted by the drilled and slotted disk brake rotors on racing cars, which is partly done to aid shedding heat which leads to brake fade. Air flow is secondary, you just need enough to move the heated air from around the engine, after a certain point blowing more air past the motor does not gain anything as the metal can only conduct and shed heat just so fast.
Orienting the head fins in line with the anticipated airflow, just helps move the heated air surrounding the head more efficiently. It prevents low airflow areas where on fin sheilds the others from direct air movement. But as I mentioned a head fin design that maximizes surface area would be the best solution.
Of course weight needs to be realistic as well. One way to cool a engine is to cool the fuel, liquid carries away heat much more efficiently than air. I have no Idea how this will effect the engine run, perhaps an experiment with some fuel on ICE can be tried. Just remember that when you cool somethng condensation forms, so your fule container has to be capped tight (alcohol loves to absorb moisture) Perhaps a quart at a time chilled down in a cooler with ice. Fill the tank immediately before the flight and try it. It would be interesting to discover the results, one things for sure the engine will run cooler.
Note: It needs to be remembered that in our application retained engine heat is what aids in combustion, cool it too much and engine no go so good.