I first staret off my hack-sawing off a part of an unused carburettor tube, I then grinded it so that it became complementary in shape to my single port one and then used 'water weld' paste to stick them together. I could have welded them but I dont have a a blowtorch and wanted to see the strength of this resin that I used. Apparently it bonds to almost anything and starts to harden within two minutes of application.
The top photo shows the 'resin weld' after its hardened and after sanding.
Lets hope it holds!