I think its a bit more complex than that. You need to consider tire size, bumpstops, and brake lines. Start with tires. How far can you stuff before they rub, that will set your bumpstops. Then, measure the distance between shick mounting locations to get the ride length of the shock. From there you will need to start searching for shocks that have an extended length and compressed length that are equally distant from your "ride length". Or 60/40 up to down. Make sure your brake lines are long enough for the "possible" droop. Last, if your axle will droop more then the brake lines and / or shocks will allow, get limiting straps. HTH
P