I'm adding an adjustable backstay to a fractional rig sloop (Hunter 30 - 50ft mast height). I'm surrounded by hardware catalogs and am trying to guess what size blocks to use. The stay will be made from wire. 1 length from masthead to a middle wire block with another wire section from transom quarter, thru the middle block to a rope multi-purchase on the other transom quarter. I need to size the wire, the middle block and the multi-purchase blocks. I have no experience and the catalogs aren't all that helpful. Can someone give me what worked for them please? Thanks in anticipation Patrick