Since I'm coming into this discussion rather late, all of my suggestions except one have been offered. If you go to the trouble of angling the end block under the peg head, you could angle the end of the peg head to fit flat against the fret board. You could flatten out the top of the peg head by the fret board to place the nut on or cut a dado to accept the nut. This probably the most work intensive suggestion.
And as Ken Hulme said, "Keep us posted - show us your solution."
Ken
"The dulcimer sings a sweet song."