You know, just a thought. You say the winch has 1/2 wire rope(cable) on it. I have no idea what you will be using the winch for but I think you will find cable of that diameter difficult to work with. Its going to be very stiff and unflexable. Go ahead and use it and see what you find. I would suggest perhaps 5/16 or 3/8 cable. Even 3/8 cable can be a real PITA. I've used winches for over 50 years, in one way or another, and with few exceptions I've found that 5/16 is more than adequate. Besides you will be able to get, at least, 2X the length of cable on the drum using 5/16. You will probably not be able to pull 1/2 inch cable off the drum by hand - you hook the cable end to a chain wrapped around a solid object and pull it off the drum by driving forward while the winch is in neutral.
If your planned operations REQUIRE 1/2 inch cable - then I suggest that TBN may not be the blog site for you. You should be seeking advice from an industrial or commercial site. As an example - my neighbor and his D6 Cat crawler has 1/2 inch cable on his rear hydraulic winch. The winch/cable assembly is conservatively rated at 20,000 pounds capacity. With a snatch block and the cable doubled back to the winch, the ratings will jump to 40,000 pound of pull.
BTW, be sure that any snatch block you buy is capable of handling 1/2 inch cable. If you later go to 3/8 or 5/16 cable the snatch block will still work.
However you do this - let me suggest that you wear a heavy pair of leather gloves. Broken wire strands, on the cable, can cut hands quite easily.
