8-speed spacing is the same as 7-speed spacing. And 9-speed spacing is narrower.
if you bought a 9-speed shifter, you can use a modern Shimano derailleur (past 199x ; any of them, except early Dura Ace, I think), and attach the gear cable on the other side of the derailleur. If you need a better explanation, I've heard there is an illustrated one on the
http://www.shimano-europe.com website.
Regards,