I too have considered this "conversion" with an 9'6" 8wt I have, but abandonned that idea since I've gotten a lot better with doing single handed spey casts. I usually use a 9wt regular floating line with it. It can be a lot of work to cast overhead all day long, especially with heavy tips, but if you can get a few of the basic spey casts down, then your work becomes a lot easier.
I dont know your casting style or ability, but trust me, you should be able to work less and cast further if you are able to fine tune your casting style to be more efficient - ie. get good at a few spey casts.
I even went so far as to learn how to cast what was a 8-9-10 windcutter now cut back to just ~30ft of the #10 wt section to make a sort of skagit line with that rod. I'd kill myself casting that line overhead for more than an hour, but I can do my double-spey all day as long as I remember to go slow and dont try to over power things. I found that I could cast that line as well as that 9wt floater nicely with my 5/6wt 10ft singlehander as well. It's amazing what you can do with the spey style once you get a good feel for your rod and the rhythm of the cast.
The biggest thing that helped me be really lazy with my casting is to learn how to single and double haul your spey casts. I suck ass at my two-handed rod, but I think I'm pretty proficient with my single handers using the same repetoir of casts. I mostly use the double spey, circle spey and a whole lot of perry poking on botched anchors. Love the "Poke"! After the poke I haul into my D/V loop and then haul again on the forward cast. I find I'm a lot more consistent with the haul than without it, plus I can get a lot more power out of a really small loop when fishing under and around overhanging trees.