I've been considering installing a Lazy Jack system also. The positioning of the lines is an issue, but not sure how critical. Some systems use blocks on the lines from the mast some, some use metal rings or even eyes with thimble. I'm also considering synthetic lines instead of wire leaders from mast. What is the advantage of wire? Looks like there are two variations: fixed leaders and adjustable lines from mast. There is more flexability with the adjustabe lines from the mast. Not sure what advantage of fixed leaders from mast?
Here are links that might be of interest:
; click on Lazy Jack system.