JJ, you did't look at the Beall when you could and now it may be too late. Their kit comes with a 60° 1/4" tungsten router bit.  Designed to use in a trimmer with their jig,
They make a pretty mean thread,
unfortunately they only offer the set common sizes.

You could try what used to be EagleAmerica.

If your first cut is too short... Take the second cut from the longer end... LBD