The Dec-Jan 1999 issue of S-T-S had a Harry Lemire concoction for a 9 wt 14' spey rod of 20' DT12F belly spliced on either end to .38 running line and a 15' sink tip of whatever you want to sling.

To create the loop connection, dip the fly line in acetone for about 5 minutes and strip off the plastic. Fold the dacron core back over to form a loop, wrap it tight w/ fly tying thread, whip finish, cement with plio-bond and cover the whole knotted area with a heat shrink tube.

I didn't like slinging 20' of DT12 w/ my 9 wt so I used about 30' of DT11 (I tried 25' but that wasn't enough). It can cast far enough conventionally and I can spey cast it easy enough also.