believe it or not, the rods are 266.7mm double checked just to be sure
Right yeah I rechecked the probe offset, and it was definitely not X+35 Y+10 it was Y +35 and X-5. However, I feel that my Marlin 1.1.5 isn't compensating for that as it still probes towards the top left. You can see in this new video:
https://www.dropbox.com/s/72kjusfudf...22.14.mp4?dl=0

about the DELTA_PRINTABLE_RADIUS the Linear plus has a 240mm diameter bed so 116 should be fine, i've lowered it to 90 and 110 and nothing changed.

The good news is at least I can start a print, the layer test, unsurprisingly the area that wasn't probed has too high nozzle and so it doesn't stick.
https://www.dropbox.com/s/72kjusfudf...22.14.mp4?dl=0

Slowly getting there but it's gah