Simplify3D to OctoPrint
This didn't fit in either
https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/octoprint-issues-and-tips-t13156.html
https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/simplify3d-settings-for-mk3-t12950.html
but thank you for the support pulled from each.
Following the simplify3d forum thread https://forum.simplify3d.com/viewtopic.php?f=23&t=1924 , I am now able to 'save toolpaths to disk' that automatically uploads a copy of the gcode to octoprints queue.
By installing Curl https://curl.haxx.se/download.html and adding this string to the S3D FFF process settings > Scripts > Post Processing additional terminal commands, S3D will upload the gcode to the octopi and without refresh will show a few seconds later!
curl -k "X-Api-Key: Your API Key" -F "select=false" -F "print=false" -F "file=@[output_filepath]" "https://octopi.local/api/files/local"