The Flair method of joining the wings to the centre section uses thin ply dihedral braces, these are quite short, and although might be adequate for normal day to day flying, they were lacking when it came to taking a serious tumble, as I'm sure the SE5A did just that. I've made up some new spar inserts from 1/4" ply. These will fit between the existing 1/4" square spars. Just in case I've prepared enough to be able to rebuild the upper wing assembly as well.
The SE5A plan shows the root ribs on the wings being set by using an angle template. I measured the angle as 6 degrees, using the angle I made up a packing block to fit under the last rib, rather than rely on the accuracy of the dihedral braces to get both wings to the correct dihedral. Might be a long winded way of going about it, but once the fiddly bits are sorted, it should prove to be a straightforward as well as accurate rebuild. The photos show the spar inserts in various stages, the saw is a "Zona", I've used it for at least twenty years, it enables very accurate cutting with a nice thin kerf that hardly notices when you cut bits apart and glue them back together. This is the way I made the LE and TE spars for a Copland 1937 Wakefield, so the idea isn't mine. Piece of scrap and a couple of clamps make cutting an accurate line easy.