Having now got the cowls as I want them I can secure the front end of the stringers inside the cheek cowls. I had been trying to work out how to get the drill into this tight space and even got a right anlge short chuck driver to help. In the end it was far simpler to simply remove the front 3 dowel pins from the stringers, carefully spring them out and drill the premarked location for the angled brackets I had made.
These had also been pre drilled for the rivet that would go through the cheek.
Simple job in the end. Its funny how some jobs make it feel so much closer to finish … riveting little bits like this are one of those !