The biggest problem I saw with the performance of the early V10s was most trucks were ordered by the dealers with 3:73s. Most 6.0 Chevys i have drove had 4:10s. Why anyone would want a tall gear in a heavy duty gas truck is beyond me. Both my 2017 and my 2000 gas F-350s have 4:30s. The fuel mileage difference between these and 3:73s is negligible, but towing with 4:30s makes those engines not even feel like the same motor. I expect the HP of the 7.3 will go up as the years go by. When the V10 was first introduced in 1998 it had 275 hp. In 2000 they bumped it up to 310 hp, and after 2005 it had 362 hp.
To the OP, I would probably go with a 7.3 right now, even though the power advantage over the 6.2 is small, it can get some pretty decent gains with a tuner.