These double sheave blocks would certainly be up to the challenge, although they are probably overkill for what you're talking about. It'd also be good to have a becket (dead end) on one of them, and these blocks do not ship with a becket. We recommend checking out some of our pullyes, which still have plenty of capacity, such as this 4:1 Mechanical Advantage Kit
. Pulleys like these are great for soft rope, but if you plan to use wire rope, we would need to find different pulleys for you. Please email us directly using firstname.lastname@example.org
if we can provide any further assistance, or call us toll free @ 800-442-7454.