After more study, research and forum browsing, I made some moore test pieces by removing oxidised/contaminated/glased wood from the surfaces and roughing the surface with abrasion just before gluing.
I used only just enough clamping pressure to hold the pieces in alignment and cured these in warm sunlight for 8 hours.
SUCCESS!
The wood is failing in all breakage tests.
I think surface preparation and low clamping pressure are the keys to making very strong glue joints.
To prove it, I will try another couple of tests with SEPERATE clear epoxy and J-B Weld.
If these joints are successful, I wont bother mixing two different types of epoxy glues.