I did indeed look 'em up... and the Jetta radiator looks like a clean, relatively simple installation!
However, I think I may still go the custom route, so I can get the hose connections, drain spigot, and filler cap/plug where I think they would be best. Either way, it's gonna cost me a pretty penny. But the way I see it, there's only one way to do it: Right, the first time!
It's cold, damp, dark, and drafty with the top up and headlights on... British motoring at its best!