v8 swap transmission questions

i got a 350 with a turbo350 trans its awsome having an automatic because its easier to hit switches but it does suck going on the highway with only 3 gears and no overdrive

http://i164.photobucket.com/albums/u31/steve-tracy/carshowapril20th017.jpg
http://i164.photobucket.com/albums/u31/steve-tracy/carshowapril20th027.jpg

I'm running a 5.0 with a C6 auto. Truck doesn't run yet, but the trans was just rebuilt with all new internals and a B&M shift kit before I got it.

This truck has a Dodge 360 in it but i'm not sure what tranny he has.