With a top loader and a 3.5 rear gear you could just about run any 'hot' cam you like for cruising in the 70-80 mph range. Cam profile is all about the rear gear ratio and thus the expected rpm range you want the cam to work in. Your rpm will be in the 3500-3600 rpm range at cruise speed, pretty high. Wide ratio trans has a reasonably low first gear ratio as well so 'around town' won't be so bad either. The over all setup I would call 'cam friendly'.
You might want to consider a 42 gallon gas tank though, your cruising range with that kind of rpm/speed is really going to empty the tank in a hurry.
I went with a solid flat tappet Comp Cam's 292S for a nice 'lumpy' idle and decent throttle response from about 2000 rpm. My cruise rpm is around 2800-3200 and that works out real nice. 3:31 rear gear, CLOSE ratio top loader.
My PREVIOUS solid roller cam didn't like the rpm to drop much below 3000 and that was a pain in the butt on the street or the freeway. Sometimes I would be forced to run THIRD gear on the FREEWAY just to keep the engine rpm up.