You don't say how far out your measurement is. If one half the total range of variation is .025" or less, you can choose one of three sizes of eccentric pins from Lakewood. They come in .007", .014", and .021" offsets.
I was not that lucky and had to do the process described by Ed above. I used the Lakewood kit for that. It's about $17:
http://store.summitracing.com/partde...5&autoview=sku
These pins are longer and will extend through your bellhousing
and the welded bushing.
I have removed balky OEM pins by locking ViseGrips on them as tight as possible and twisting them out. I have also ground a flat side on them to get the ViseGrips to hold better ... if you don't have a welder handy.
Good luck!
Sam