A little update. I purchased one of those BeCool adapters from Jeg's, but I modified it a bit:
First, the sawn ends of the pipe were pretty rough, with a lot of "flash," so I cleaned that up with a file... don't want any of it breaking loose and flowing around in the engine.
Second, I broke out the ol' Dremel and cleaned up the interior weld where the two pieces of pipe are joined, since it was pretty rough, with some "spikes" that stuck in over 1/4"
Third, I changed the grinding wheel for one of those little milling bits, and took off most of the interior of the bung for the drain petcock. The actual petcock is primarily threaded into the portion of the bung that is external, so the internal portion is mostly just a restriction to the waterflow. So, I took off all but like 1/16-1/8" of the bung, which opened up quite a bit more of the pipe, and should reduce the amount of cavitation. (and, just in case anyone doesn't realize this, you need to take the petcock out while you do this, but you should periodically re-install it to check depth - also, it's a 14mm hex, not 9/16", so don't strip it trying to use the wrong wrench)
Lastly, I fired up the wire wheel and gave it a brushed finish, then put some Teflon tape on the petcock threads and re-installed it.
Joe