Details on the modified chugger pump head? Is it welded drilled and tapped for NPT tri-clamp fittings?
I just welded two tri clamp end caps onto a center inlet chugger head for a HBT member and it ended up looking similar to this one. The owner drilled the holes in the end caps, removed the threads on the ends of the ports, and I welded and ground the faces of the end caps.
Kev is right, I took two end caps, drilled a 3/8ths hole through them using a hole saw and lots of oil. Cut half the threads off both sides, ground down for a snug fit and then tig welded the flange, then smoothed it out.