The drop shackles for the chevy are actually very long... Some advise against using the long shackles because they can and do put more stress on the spring with the increase distance and leverage... You can pick the drop shackles off of ebay, usually they have 2 holes for different heights.
But if you have plans to get a new axle anyway, why not wait, find one with the right gears, and do it right when you can? No sense in doing things twice, buying cheap parts to net small lifts now, or just save up for an axle, have a member help burn some perches on, and get it done right in one shot.
Rob L.