You could do a big single. A lot of 5.0 mustang guys that run fast times have gone turbo. Are you on the stock bottom end? Port your stock heads, and throw a "turbo" cam in. What are the specs on your current cam?
Also, as far as picking out a cam goes. It seems that 114 lsa works well with most turbo setups. You need to figure out what kinda setup you wanna run before you can pick out a "perfect" cam. If you do twin-turbo, will you be using a log or an equal length manifold, ect ect.
Also, it's not good to have a lot of overlap on a turbo cam, and people generally run more intake duration then exhaust, like you would on a NA/Supercharged/N20 cam.
http://www.cmotorsports.com/engine/lt1-lt4...aft-design.html
That's a good link. Look at the specs on each cam. Their turbo cams have no overlap at all.