This was really simple to make with a dremel, Loctite Repair Putty (or JB Weld Water Weld), and the two fittings you want to use (they’ll be permanently locked in).
Dremel’d off the external plastic flow channels, leaving only a bare inlet where the water enters the volute and an outlet hole where the previous outlet was. Started sealing with the Loctite putty over the structure and then placed the fittings and continued sealing the putty at every imaginable seam. Continued with the putty until the structure seemed evenly made and leaks wouldn’t happen.
For leak testing, connect to a pump and run it. If there are leaks, patch it up with some RTV epoxy.
Laing made a great top, this mod just allows for full performance and compatibility with 1/2″ and 7/16″ tubing.
Aesthetically, product is unfinished and unrefined, no make-up was applied, but a sanding and painting could make it look pretty good I bet.
Further refinements could include compatibility with any G1/4 fittings if you want to drill and tap the inlet/outlet rather than permanently install the fittings.