Ok, it looks like LRP made some new inserts for the 20 and put the degrees on them but only on the low side, not on the high side. Dumb. Here is what you need to know. The sensor has 37.5 degree of timing built into it so if you look at the insert that has no angle built into it, that should also say 37.5 on it.
Then there is one that says 35. That means it is reducing the timing by 2.5 degrees. So if you reverse it, that's adding 2.5 for 40 degrees.
Next is 32.5. That's 5 degrees back so flipping it is 42.5.
Then 30. That's 7.5 back so reversed is 45.
And finally 27.5. 10 degrees back so backward is 47.5 and max timing.