Thank you so much!Strength is not an issue, so any modern line will exceed the expectations for strength and stretchyness (It's an industry term ;-) ).
The most important factor in the line thickness is the "hand" or how it feels in your hand. So, too narrow lines will make it harder to get a good grip. I believe I tried to match the spec diameter as best I could and simply used the Sta-set polyester yacht braid from New England Ropes (available thru West Marine).
For length, have the shop cut them a foot or two too long to provide for knots and refinishing the ends.
If you have a color coding you are familiar with, go with it, I do not know of a normal or standard color coding for Capri 14 lines.
I bought a fid kit to splice on the halyard shackles, but a simple bowline works fine to get you on the water.
I skipped the block and becket on the jib halyard. It didn't seem to serve much purpose to me. And it kept the jib from coming down far enough to secure it on the foredeck between launches. To get the length, I measured the height of the block about the deck and did some trig to get the distance from the block to the bow, then added a few feet for tail. I then trimed it and finished the ends after I had sailed with it and marked the length I wanted. (I would love my comment about not including the block to trigger a thread on how to rim Capri 14s in high wind. It is something I can do luffing the main, but the rig doesn't seem to like the transition between tight and flat to twisted off with some luff. And by "it doesn't like it", I mean I haven't figured it out.)
Good luck and have fun!