This is my second MKII for a Gibson LP and the one thing I wish this came with (both times now) was a second set of washers and nuts for the pots as I've had to elevate the board in the cavity so that the knobs aren't floating way above the body.
Also, the toggle switch doesn't come with a recessed/deep nut for carved top LPs, so I had to swap the wiring and keep the existing switch (because the recessed nut on the stock Switchcraft switch wasn't compatible with this Switchcraft switch - which isn't that big of a deal, but is kind of annoying and it does mean this is not a totally solderless install if you're swapping over from something like this.
Most of that could be interpreted as personal preference, but a kit like this should at least assume some of these things... or at least provide options for these things on checkout.