Here's some pictures of an airplane I had built and flown for a number of years. The rad is placed under the engine on a slight incline with the rear end of it being the high point. I installed a bleeder valve at that end to get the trapped air out. The "front" has both inlet, and out let hoses attached to the end tank. To make it work, I welded a baffle plate in the tank to partition it off. The coolant would enter, go down one side of the rad, across the end tank and back up the other half of the rad and out. Other than that, your looking at a regular ol' Chevette rad core and tanks. This might be a bit more extreme than what your looking to do, but the point being, it can be done and it works fine. Just provide a way to get all the air out, (bleeder valves)and a high point to gather the stray bubbles, (expansion tank) and to be able to add coolant when needed. Sniper