Remodeling a fixer upper,ceiling needed a 4 ft by 5 ft piece installed from water damage.
three sides came out level and nice but one 5 ft side came out bad unlevel,recessed about 1/16 th to1/8 of an inch.My dad tried to plaster it sand it and called it good after painting it.water damage restoration

Remodeling a fixer upper,ceiling needed a 4 ft by 5 ft piece installed from water damage.
three sides came out level and nice but one 5 ft side came out bad unlevel,recessed about 1/16 th to1/8 of an inch.My dad tried to plaster it sand it and called it good after painting it.Is there any way to fix this to make it level on the one seam that he missed?
He is thinking of sanding it or grinding the existing drywall to level it up to the patch but I think you do not ruin something that is in place and good to TRY to make it level with a patch.water damage baytown tx

You can't rely on drywall as a solid sustaining material, you should also use some more resistant materials in the mixture. You have a good plan here and most likely you'll succeed with the project but make sure that you use the right drywall, there are some issues with the Chinese drywall that will turn the construction industry upside down, just like asbestos did...
Sally, Chinese Drywall Attorney

Roger,

I run into this type of problem all the time, though not usually to the extreme of 1/2" variation. If it is up to 1/4" you can usually use a utility knife to trim the corner of the drywall enough to let the trim lay down. This can be tricky because the finished miter must be a compound cut to close right. For variations of 1/2" I seriously would not recommend this.

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I'm hesitant to build jam extensions for fear that they'll be very visible. But I'm not sure if there's any other option.

Why? If you do wooden jam extensions, your problem is solved and the finished job will look 100 times better! How is the window wrapped right now??? Don't you have to install jam extensions? If you are worried because there is a dip or belly in the drywall in the middle, that can be dealt with by running the side jam extension over a joiner, or use a hand/electric planer so that you trim off the corner edge( the one that will be covered by the trim). That lets the trim turn a bit if the extensions sticks out past the drywall, but still look good on the visible corner. If the drywall in the middle stick out past the extension, bevel trim the drywall with a utility knife. Make sure you don't go farther than the thickness of the casing material.

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Also, I'm debating doing mitered corners versus butt joints in a rustic/farmhouse style. At first, I was leaning towards the butt joints but I wonder if the uneven drywall will be even more of a problem since the top piece of trim would extend out further, overhanging the vertical pieces a bit. (My test pieces touched the drywall on the two ends with a gap in the middle. Ugh!)

This can be dealt with, but it will be work. You can use a router or even a planer (depending on what needs done) to make the top piece thinner (or thinner just in places with a router) so that it lays 'flat' and does not stick out past the side pieces. You basically 'hollow out' the casing.

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Finally, I'm recycling some southern yellow pine flooring for the trim and am wondering about routing an edge to give it a more finished look. Any recommendations on bits/profiles to use?

If you're looking for a rustic look, two options look nice. A small bevel or chamfer on the corners, or a 1/8" round over. This depends on if you want a 'squared' look, or the round look. Either way, hand sand with 150-grit after you do the routing, before finishing.

Can you get some pictures of what you're dealing with? It may help me explain things better.