Not able to properly test flow out until the backside is done, but I'm sure, (going on past experience) it will be more than sufficient flow wise to cool the chips. The 'lug' area is bypassed both sides and is not the most restrictive part, although in hindsight maybe I should have used the hole above, but when designing it I wanted to use the same holes as the reference sinks use, not all the holes in the card are used by the reference cooler.
The initial inflow outflow area is probably the most restrictive, where is enters and leads down to the main channel & the same on exit. I have just made a testing block out of a Perspex offcut so I can leak test the block. pics should explain this, just bolts to the block in the same way the backside part will and seals against the O-rings. The other side of the Perspex has some 6mm Festo for testing, (backside cooler will have 8mm Festo).
I also like that heatpaste pic too
and was happy to see it contacts all the chips after all the intricate set-up work making it entailed. The actual height difference between GPU to Ram chips is 1.62mm, (best I can measure it), so when the block is bolted down firmly it just slightly bends the card in the gpu area, giving good contact pressure on the GPU.