I've an idea how you could make it work. it'd involve a 'blanking' plate with holes in (a circle of then at the radius of the blocks circle) for water to 'vent' up into another chamber above, which would house an outlet barb. there are calculations to equalise the flow(the outlet would be off centre, and least resiistance being what it is...) that I'd need help with.
Hopefully this would stop any 'crossflow'(wtf?) where water is trying to get to the outlet, the flow would be symetrical(is this as important as I think in a radial block?)...
It should be workable, just have to calculate the holes size/amount so it does'nt create to much(or any???) back pressure...
Utabintarbo has offered to make up a model for me, I've just got to find time to ink up a drawing and scan it(my scanners in a cardboard box
), and upload it to him...