[socal c25]

I am going to do the same on my Coronado 25 BUT I am going with 3/8 as its easier on the hands AND I have the lines ready to come back to the cockpit, cabin top winch and rope clutches. I do have to change the sheaves cause I don't want my lines ruined by the grooves, I am also going internal and coming out the bottom of the mast. The red line in the pics is a fake just to line things up.

 

[socal c25]

All rope halyards are good enough for me, I just cruise and I am not looking to squeek out an extra quarter knot. If the halyards stretch it was probably cause I had em too tight to began with (bad habit). With the lines aft to the cockpit I can always adjust them as needed.