Hello Jim,
you should have a look on this former thread in this forum https://forums.jag-lovers.com/t/xk120-fhc-ndv-buildup-pics/364552. Especially to the pictures in the posts no. 17, 26 and 30. There you can see a sheet metal bow, partly covered with plywood. The fifth list stick is screwed to this sheet metal bow in the gap between the two plywood fillets.
Regards Joerg