454 Dually....5.3 Swap....Pros and Cons.

[Ford Assassin]

Hey guys, I have a mild 454 mated to a NV4500 in my 88 R30 dually. I get 14 mpg now highway, but under 10 in town.

I am considering swapping in a spare/fresh Gen IV 5.3 into it and retaining the NV4500. I tow about 6 times a year, but it it only weighs 3500 lbs. I have done no less than 20 LS swaps, mostly with a turbo, but nothing in something this heavy.

I am after better MPG without losing a bunch of towing ability.

Thanks!!