I think if you want the speydicator you'll probably need to size it down to a 4 wt (280 grains) or 5 wt (350 grains). It's been a few years since I played with a batson 7 weight switch. I remember thinking it felt awfully light for a 7 weight, but that was before I, too, knew those blanks were rated for single hand.
I looked around and found the grain window on this blank to be 185 to 380. You might want to talk to the guys at Batson, talk to Poppy at the Red Shed about demoing a line, or give Steve Godshall a call and have him make you a custom line to do exactly what you want it to.
"Perhaps fishing is, for me, only an excuse to be near rivers." - Roderick Haig-Brown