You're not the first person to run SS springs with lowering blocks. People have had them de-arched as well, although that requires taking them off and hauling them to a spring shop. Since yours are brand new they will definitely settle, some settle quite a bit. The XHD's I put on my Challenger settled a couple of inches in the first 6 months. So I would just run blocks in the meantime. If they settle down too much you can pull the blocks later. If not, the blocks don't really hurt anything as long as they aren't super tall.
