Hi Uncle Craig -
I like the Windcutter 9/10/11 on that rod for a very positive feeling cast even with the type 8 15ft tip on it. Just strip to the head, set up and feel for that "whump" as the strong tip comes over the top to punch the line out there.
I have recently obtained the SA Short head spey which I think will also make a great tip system for the rod. For XLT I prefer the 7/8 XLT on that rod, in fact I LOVE the 7/8 XLT on it.
The Airflos are great on it, already mentioned above.
So if you like a shorter tip system go with WC or Delta, for a longer (minimum strip) line I would go with the 7/8 XLT cut and looped for tips per the speypages discussion -or- use the 8/9 you already have but you might have to cut and loop again to take the sinktip.