Those CPUs are going to be very difficult to cool. They may outperform the 3700X and 3800X in multi core performance in the Velka 5, but they will still not be used to their full potential.
Curious, could you use the Alphacool Eisbaer LT pump/block (39mm in height, side fittings) + 2x80mm rad mounted externally on top of the case, with thinner tubing routed through the I/O area and have a watercooled Velka 3? It should all fit, right? I'm guessing you'll need thicker externally mounted fans too as the 80x10 ones will struggle to push air through a radiator.