If you go with a shackle that is 1" taller than stock which is 1/2" lift (amount of actual lift is about 1/2 the difference between the 4" stock shackles and the new ones), you should be ok, and should not notice any changes in your steering. I would recomend getting them with greaseable bolts.
This guy makes a decent product, he made mine:
http://cgi.netscape.ebay.com/ebaymot...tem=2447082439