good work CJ! i am glad you are getting it sorted nice idea to relic the hardware a bit too, i always thought it was going to be best to accept this guitars age and level of wear rather than make it look like new.
There's a big chance you'll see the contours of the inserted wood through the finish no matter how well you fill the cracks and sand. Instead of normal filler, use fiber glass filler for the cracks.
When filler dries up it shrinks a little and usually stays a bit soft. Fiber glass filler doesn't shrink that much and becomes very hard, almost stone like.
It is a bit harder. It's OK if it's on the surrounding surface. Just sand it smooth with a sanding block.Then go over it with regular filler and sand that with a block too. You can check how level it is by applying a little spray paint between the sandings.
Cool ! :lol: