I think either one is a good choice that can work fine, but the Chevy 454 might be slightly better mileage vs Ford 460, all else being equal. Seems the 460 are more thirsty. The other factor is the transmission and chassis, since those will be corresponding to the same mfr as engine. The Ford's in late 80's/early 90's had worse trans than the GM which would tend to favor the 454. I would call the rest of the chassis parts a toss-up.
Once Ford switched to the V-10 it improved both the mileage and trans fitted to the engine. Gm switched to the 8.1 as the big engine in place of the 454, which is basically a next generation 454. Still a good engine like the 454 was.
Above comments are just my opinion, interested to see what others say.
2005 Kenworth Showhauler truck conversion.
. 44 ft, Cummins ISX15 450 hp, 10 speed, twin screw
I used to have a handle on life, but it broke