unless you have a diff blower the eaton will max out pretty quickly on a turbo setup.
by that time it'll be a restriction rather than a help.
stock heads will be fine on a turbo build, but porting will def help especially if you get a nice turbo cam.
yes turbo lag sucks...but at the same time how much power is actually usable in those low rpm's? usually low rpm power translates to wheel spinning. our 3.8's have the capability for a lot of torque as it is.