MIMF

Just curious as to what you do to fit a slightly oversized Precision bass neck to a slightly undersized fender style body?
I assume that I just take a wood file and make the same number of strokes on each side of the bass cavity until the neck drops in, but you may have some other way. This of course with tuners, bridge installed and outer strings.

I would probably take the neck down a bit, it being easier to get at. I probably would have discovered this before it had strings on it. Keeping it square to the body, so the strings lay properly on the neck, is very important.

Don't remove the original neck finish if you can help it unless you enjoy refinishing necks. If you do remove the finish then straighten out the fingerboard edges while you are at it and think about re-carving the neck to a thinner profile if it's one of those monstrosities from Warmoth.

Otherwise:
Clean up the sides of the neck with fine sandpaper on a straight board to clean up any finish drips or random bumps.
Create an accurate cardstock or thin plywood template of the outline of the neck heel with a centerline marked.
Mark the centerline on the bass body with masking tape between the center line of the neck pocket and the middle of the bridge. If the bridge isn't mounted yet use the centerline of the pickups, the strap button hole or a full sized paper plan to establish it.
Line up the centerlines and score the new neck pocket lines on the body and trim the excess with a sharp, wide chisel.
Check with a small square to make sure that your chisel strokes are on target.

I prefer to fit the body to the neck, at least when that is appropriate and especially if a lot of material must be removed. If the neck must be fit to the body, I would tend to work wherever it will be the least seen and the least material removed. If the bass side of the neck fits well and is aligned with the bridge well, then a small amount of material may be removed from the treble side to fit the smaller and less visible side of the neck pocket. If the neck does not align well with the bridge when touching the bass side of the pocket then be sure to make the contact points with the pocket as large and even as possible.

It worked, I scraped the neck pocket of excess finish, a little sanding and it fit thanks for everything