This is the proverbial weak link in the chain. Something will give eventually. Do yourself a favor for the peace of mind, replace the 30 year old shrouds and turnbuckles. It won't make you go faster assuming you already tune for your sails, but it will sure make you sail more confidently knowing you don't have to worry about the rig coming down.

I agree with Vic and wouldn't use an aluminum backing plate. G10 is definitely the way to go.