adding runners for staysail

[buckborough]

this query concerns a 42' sloop designed during the cca era to which i am considering adding a staysail. so, in addition to the staysail stay, i must add runnings backstays. what about those running backstays? can they be fiber - one of those new high strength low stretch uv resistant lines? which one? and what about the tensioning apparatus? i had thought to use a four part block and tackle arrangement with cam type stopper shackled (or similar) to the lower end of the stay. do you think i could get enough tension on the stay without taking the purchase to a winch? should the tackle have more parts? or should i consider some other type of tensioning arrangement - something simple and robust? thank you kindly for your thoughts on the matter.