Mounting: the block fit perfectly on the core even with the "lip". Didnt have to do any modding or anything. Just removed the HSF and all the crap and applied some ASIII.
Barbs: simple USED THEM
All the blocks in my system were already 3/8" and I just split the 1/2" line using a "T" into (2) 3/8" lines; one to the CPU and the other to the GPU. Worked fine for me.
Pelt: If I ever get that far, I will probably use a smaller pelt and then replace the plastic locking units with small screws and go at it that way. I am still in the "thinking" stage of that endeavor. I was looking into useing the Thermatake solution as the PSU and then a 56W pelt (if I can find one) or an 80W pelt.
Block works great though! Very happy with it.