What is the best method...

[Kevin Sjostrand]

On the first kit guitar I built, later when I wanted to install a pickup system, I discovered that the end block was too thick for the end pin jack, so I did just what you did there. I flattened and sharpened the bottom wings of the spade bit and counter sunk, or cut back the inside of the block enough to lessen the thickness so the jack would work. I think I used a 3/4" bit and it worked like a charm. I believe it cut cleanly, but of course it can not be seen down there.
NOW I make my end blocks thinner; 5/8 to 3/4".

Kevin