Custom Cometic head gasket pics

Not arguing against this idea overall, but I can see most of the coolant taking the direct path to the outlet, which is past the the front 2 cylinders in the head. There is nothing that will force the coolant for flow to the back, and IMHO it will suffer from lower/starved flow as there is more flow restriction going that way simply due to the longer path. In fact, I would not be surprised if the coolant going through the #2 and #3 lower coolant holes would push back a bit towards the back and stall any flow coming up from lower hole #4. I am certain that is why the stock holes ARE restricted in the places pointed to by the arrows.
I'd be putting some mild restrictions into the #1, 2, and 3 lower coolant holes in the block to attempt to equalize the flow up to all sections of the head.