if you look at those clamps, the bolt pattern is not offset. That won't work with the radial pump master the OP was referring to.
Unless I go for the RCS type
No, I have to draw the line somewhere - those RCSs are nice, but overkill for my budget and needs.
I'm waiting for responses from a few good vendors, who are trying to help
I'll post what I find out. Not a huge issue though - I'll probably do fine with the slightly larger (16mm) coffin master if I must settle for that.