Just a suggestion.
It seems you can "Partially" get away with copying certain design elements, without breach of copyright, it seems the Headstock being the problem.
Since headstock templates are available online to be easily downloaded to replicate the END of the headstock [which are the copyrighted portions], the need to choose between the end of headstock [copyright] and headstock to nut tapering/shaping has, IMHO, been skewered the wrong way.
My ES-1 Kit neck has the classic [copyrighted] Gibson end of neck Tulip shape, but differs at the neck joint....as a guitar builder, which is more important?, the neck/body joint, or legal troubles because of headstock copying?....fix the neck joint, leave the headstock flat so purchasers can sort it themselves......[neck joint problem with my kit]...I'll post photos.
The ES-3 has a flat headstock end [so design away], but the taper of the neck differers considerably from the headstock to the nut.
I don't think that has been copyrighted, as it's a matter of structural integrity of the neck [I know, Gibson and Neck headstock structural integrity shouldn't be used in the same sentence ]
The ES-3 Kit has one particular bigger problem than that though [actually several-needs a construction rethink as a kit] .....I'll take some photos and show you....it is particularly bad, and quite frankly, I'm surprised it's sent out as is for people to build.
[It's where the body meets the neck at the LOW E side, there is a gap of about 1/1.5mm ]
I used some lateral thinking, and have thought about doing some slight Internal modifications, and glue a small block of wood under the guitars top, so it can be clamped against the fixed neck, when it comes time to do so, thereby closing that space....there is plenty of space to fit a small clamp inside the body that would do the job