"If those are pre-load tensions, they sound a little on the high side."
A little?
A thousand pounds sounds damned high to me. Even 700 sounds damned high for most sailboats at rest.
What's the normal working load for 1/4" stainless shrounds?
AFAIK it would usually be spec'd at 20% of the rated breaking strength, which seems to run 6-8,000 lbs. for 1/4" stainless cable...So a rating of 1200-1600lbs. on a fully loaded cable would be the maximum working load to put on it. I can't think 1000 lbs. would be the correct "slack" load for that.
I could be totally off on that...but personally I'd drop all those shrouds down to maybe 300-500# until I could find reason to set them any tighter.