mhh. I just got a brandnew rim/tire set in black for the original BMW fork. So I do not want to change the front rim just for a WP fork. I also can get a Xtrig clamp (TE310 etc.) for the top which is around 54mm for the fork. So this should fit a WP fork from 2011/2012 coming from a EXC-F 350. I have an offer for a fork from a KTM EXC-F 350 2011/12.
The brake and the steering-head and the lower clamp of the G450X should fit.
What did you change? Do you have fotos? I think I have to change the shell/bush on the brake side.