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Hey everyone, I wanted to do a bit of a follow up on a repair I'm doing. A customer brought in a Seagull acoustic guitar that had been dropped, causing the heel block to separate. I managed to get that glued back together with pleasing results, however I did need to take the neck off by removing the two bolts which thread into the heel block, and unglued the fretboard extension. All went well here, although I'm left with a situation where I could use some advice. I've spoken to a few Looths in the 24 hour chat, but I wanted to make a post that I could refer back to.

So I very gently cleaned up the underside of the fingerboard, just to reveal what I was working with and remove a bit of glue and wood fibers. The center portion is fairly clean, although it drops down near the edges, to nearly 0.20". Additionally, the body joint has a similar "radius" to it, where it's high in the middle, and drops down at the sides. It also has this type of figure going back to front. So the question is, how do I proceed? I was considering getting the underside of the fingerboard and the top of the guitar both flat, and then adding a shim between those two surfaces in order to have them mate properly, although I feel like this may be a bit hokey. As it stands, there is a fairly significant gap between the underside of the fingerboard and the body, and I can stick a feeler gauge of about .022" in the gap (which you can see in the pictures). Any thoughts on how to proceed here would be appreciated. Thank you!