As far as the space between the keel and rib: If you hate the bending process, you can add a spacer (block of wood) in between the rib and keel or make a new one. That problem usually occurs more on the sides when trying to get a fairness with the chines. Most builders have to use a block or two on the chine stringers. Don't pre-cut the rib stock to length. Bend a longer piece, fit it with the ends fastened out side the gunnels then carefully trim it to fit.

Forget pine for bending. Sand the bending area on the rib stock thin on the 1st and last rib. Even very thin ash will be quite strong because the shape of that small bend lends itself to a lot of strength. Worst case, use two pieces of rib stock fastened to a "V" shaped block.