Webmedic, I'm looking, I'm looking, patience my friends
Brad why on earth would you need such large block if you won't use two TECs, that's complete waste of space, it won't cool better than some good designed 60*60 block, and also this design doesn't look to efficient to me, you've got nothing in the center where all the action happen, you're going to have some death spots behind those T fins, plus block being so huge the water will move very,very slow inside, because there is just one water path with very large cross section and even that gets split two ways so velocity is again halved going left and right, no,no, this would be very bad the more I look at it, sorry. Design block the way you keep velocity at max and keep surface area large.
It all abot proportions if you got inlet cross section 120mm2, you want to have (if you're thinking two outlets) inside paths 60mm2 going in two directions, maybe a little larger if your pump can't handle a lot of preasure drops, or even smaller to improve velocity->heat transfer if you have pump that can do that.