I thought it does, but not sure of the magnitude.

If you think of a super long fork (chopper) with the same rake, well, the trail would be very different than a "standard" fork length.

Having said that most forks have a standard dropout to fork race height. So for standard calculations length is irrelevant. It becomes significant when dealing with an odd length fork, i.e. suspension, diff wheel size, etc.

A long time ago I used a head tube facer to "mill" away about 4 mm of my head tube (the bottom) in order to drop the frame a bit. I also used a fork crown race facer to mill away perhaps 2 mm off the fork crown. Not sure if it helped but the long night I spent doing it convinced me that it must have helped. Probably got like 0.1 degrees. lol.

cdr