I didn't have any issues with my radiator from Summit, but I bought it several years ago. Who knows, maybe the radiators are made in Taiwan now.

If there's a gap between the edge(s) of the shroud (left and right sides I presume) and the radiator, can you just place some black sticky-back foam weatherstripping between the shroud and the radiator? Maybe the $3/roll stuff from Home Depot. Just don't use the large open cell style weatherstrip, I don't think that will take the heat, but the standard black (something like 3/4" wide, maybe 1/4" thick), would work. You could stack one piece on top of the other if you need to go thicker, because it has a sticky back.

Even without the shroud sealing all around, I would think you could still see if your car runs cooler now. Just make sure there's enough gap from the fan tips to the shroud! I made that mistake once, started the car up, sounded like a machine gun going off as the blades whacked the shroud on one side.