Ok guys thanks for the pointers. The mower wasnt the easiest to work on however it came up a treat.
The carby was relatively easy to work on. I just took some photos as I went to ensure everything was as it should be once it was back together. The carby was full of stale fuel and dirt however once it was cleaned up it started first pull.
The mower powered through the long grass when tested and idles very nicely. Just like a Briggs Quantum actually. I do find the Quantums easier to work on.
I have included some photos below to help others and a picture of the throttle plate I made up as per Marks suggestion. Its not perfect by any means but it fits nicely and does the job.
Well others might not rate tecumsehs, I have done a fair few now and whilst a bit fiddly to work on I never get complaints about their ongoing performance.