Are you trying to keep your old 6 sp rear derailuer and use it with STI? I doubt that would work. If so you may need to get the Modolo STI shifters. I converted my Bob Jackson, 531 steel frame, from 7 speed to a whole 9sp 105 group and it went just fine.

As for keeping some of your old parts, I can't say. I wanted everything updated so I replaced it all. Go to www.roadbikereview.com and place your question on in the Components forum. There's a lot of people there who will answer all your questions.

you will need at least an 8spd derr. you should also have the rear triangle spaced for 9spd, because even though you can bend it, unless it is cold set with the der hanger aligned, it will have slight shifting problems.

tommy