Does anyone have an "easy to use"technique to determine what the static engine down thrust is?

I can establish a datum line at 0 degrees. The engine has been mounted but currently is sitting in a box (doin' a bit of reconstruction due to unknown damage). I have a large selection of props (9"up to 14"). Someone had shared that static left / right thrust could be deterimed by measuring from both tips of a 12" prop back to the fuse end (48"). Each 3/16" difference equated to 1 degree.

TIA,