Thanks for the advice everyone, the leak is indeed from the old heater coolant transfer pipes
not the new stainless radiator coolant pipes.
So now I have to try and get the old pipes out and new ones in, with the engine in situ this is not going to be fun. I'm not going to rush into this I have some time to figure a solution so I am going to think a bit and really see what I can and cannot do before making the next step, I really don't want to pull the engine out again if there is another way.
Lesson learned, should have pressure tested them before re-assembling everything. oh well live and learn.
Bart.