Amanco Hired Man Governor Latch speed control spring diameter?

Hi Can anyone help me with the external diameter of the "Hired Man" governor latch speed control compression spring external diameter .
I'm currently on with  fabricating a latch beam and would like to find the spring external diameter so I can machine the spring pocket to the correct bore size.  Thanks in advance.

The speed adjusting screw is, I think, 3/8 UNC, so the spring has to be a slide fit into the hole with this thread. The outside diameter of the spring on my Amanco is about 0.33 inches. The spring is not a tight fit so anything suitable around this size will suffice.

Many thanks Blue Cat for your help.
I've tapped the adjuster screw to 3/8" UNF so now I know that I can use a spring to fit into the 3/8" bore size. I wasn't sure if I needed to bore out to a larger size for the spring pocket.
I'll only need to experiment with the spring rate or strength when I eventually get the engine running.