To eliminate the critical precision involved, just make some hardwood sleeves that the screw shanks slip into. Then just bolt them down to the existing mount blocks, without the wing. Now take the wing and completely hog out the original holes enough so that you can just lay it over the hardware you have stubbed out from the wing blocks.
At this point get everything lined up "just so" and mix up a slurry of epoxy and sawdust and work it into the voids between the wing and those sleeves. You can also just pack the voids with dry sawdust and saturate with thin CA. I almost forgot to mention that you want to prep the area with clear packing tape so you don't glue this mess to the fuselage. You also need the wing to have ample "meat" [balsa block] in the bolt areas for this idea to work.
To finish the job, back out the screws and trim the sleeves flush with the surface of the wing and if applicable, countersink the screw holes for countersunk screws.