After a lot of thought decided to plumb the waste gate straight off the collector under the turbo.
I know it's probably not the best location for flow but there was really not enough room to run three separate runners.
Here's the pipe tacked up.......
...and test fitted in engine bay.
Pipe welded on and wastegate fitted
And bolted onto engine
Next is step is to send it off to get the mounting faces machined flat.