hmmm, the rad sounds like the Dangerden double heatercore
http://www.dangerden.com/mall/Radiators/heatercore.asp botom of page.
a barb at each end will give you a "single pass" radiator, with the least restriction, but a bit more hard to place in most setups.
pumps are best with feeding of a reservoir, or each other (res->pump->rad->res->pump or res->pump->pump->rad) the last one will work best. If you place a res after a pump, it will give flow restriction.
If you want to improve the design of the dangerden double core, you could make it a single pass radiator, and give it more hight instead of 50mm make it 70 or 100mm.
It will be massive!
I don't know how much heat you need to disapate, but this baby will keep the water even a peltier system cool.
If you want to go for a low airflow radiator you better "stack" them and let the fans suck the air through.
...........................cold air
to cpu <- out |-------------|in............|air flow
pump -> in.....|-------------|out.........|
..........................fan fan.................~
............................hot air
So it's still a dualpass radiator, but in this case a dual layer.
If you look at the smaller radiators, they are all making several layers, to gain on cooling surface. With yours you already have a masive amound of surface, but if you want to get more, you can increase the size of this baby, or make layers.
If you found someone who can build a radiator for you... I suppose that person should have all the technical background to make the best one for your setup...
