Chain Plate Sizing

[Storm]

The pin size for all the existing chain plates is 1/2 inch. I was able to obtain the original S&S designs specs for the boat's original design and all the wire was specified as 5/16 inch except for the forward and aft lowers that was specd for 1/4 inch. The chain plates were specd at 3/8 inch for back stay and upper shrouds and 1/4 inch for the forward and aft lowers. The dimensions given for the chain plates look to match Skene's.

Looks like I should just up size the back stay chain plate to 3/8 inch thick. I plan to just stay with the 5/16 wire all around. The original S&S design (1968) called for wire to be "BSF". Would you know what that stands for? A search shows no reference to BSF and just curious what it might have met.