A little complicated to explain. I fabricated a ply doughnut glued to the top of the cowl. I glued two 3/16 aluminum rivets (one on each side) with the head toward the spinner, and the shank projecting toward the fuselage. That gave me two "pins". I glued 2 tabs to the chin, that had matching holes such that I could angle the chin into place, then raise up the aft section into position, and screw attach to the fuselage through the rear upper corners of the chin.

Clear as mud???

Les