Wow--pretty cool when other posters use my boat as an example!!
I reinforced my sidebars because I run with a headsail and the bars would bend up at a VERY nerve-wracking curve. I drilled a hole in the lip of the boat and installed the same parts off of a Hobie 16. I used the bow tang off of a Hobie 16 at the top to hook the wire into. I am fortunate enough to have a hand swager, so I could swage the wire directly on the boat and not have to measure. Before I did that, I just used some line and tied it down.
Really, the sidebars should be able to take the pressure of a stock 14 or Turbo. It depends on the corrosion around the chainplate. You really need to check it out before you go sailing to see if it has weakened.
It sounds like you are sailing in salt water, so it would be a good idea to remove the chainplate and re-rivet it. Before reriveting, I would put some tape under the chainplate to keep it away from the sidebar. This would prevent the reaction between the stainless and aluminum.
Hope this helps.