experimenting? Hehe, it was more like "what will hold this lead sled down". I bought two springs at the hardware store. Originally I was going to use one, but my barbs were too close together, so i figured two would work. I seem to have picked a winner though. My Vcore is at 1.90 and my 700 is oc'd to 901 @ 29c; 23c ambient right now. There is no flow pattern within the block. here's a pic of the block, next to its top (before cutting and brazing).
The holes were originally for an acrylic top, but i broke a drill bit in one, and couldnt get the acrylic, so i just soldered them shut and soldered a top to it.