Steering box sector shaft issue

[AttackOfTheSlantback]

Hi guys!
I'm hoping to get some advice regarding the sector shaft installment on a 1937 Slantback. I bought a rebuild kit on Early Ford Store and things have been somewhat smooth so far. But, after installing the new bushings the sector arm won't fit. After grinding the arm for hours with some 150 grit paper I've managed to come maybe halfway, but it doesn't feel like the right thing to do and I'm worried I'll manage to make it sloppy and uneaven. Are you supposed to ream the bushings when installing? Anybody been down this road?
Thanx!