If you can find a '96 model 5.8 it will have some of the pieces you need to swap to a round air filter, either stock or K&N type. The round filters do have a lot more surface area and will flow more.
Here's a pic without the round air box but with the y-connector and 4" U-bend. Your twin hoses from the TB will be different on the 460.

You'll need the connector, U-bend and air box. These are not easy to find at JYs.

Well shoot, maybe I will just go find a stock air box and put a dry K&N type filter in it. . . .

Like Mark said, increasing air flow to the 460 is not as important as having cooler air.
Your ECM is a Speed Density system which means it's programmed for a certain air flow at a specific throttle opening, manifold vacuum, barometric pressure, etc. So a lot more air can't properly be used for HP. Because cool air is denser, one of the things it can use to richen the A/F and make more power is EAT/ECT or entering air/charge temp. Once it "sees" the cooler air it'll increase the pulse width to the fuel injectors to match the denser charge and even modify the ignition curve slightly based on it's programming. It'll make a little more power at the same throttle opening.
It helps the big motor's MPG as well. You can use a little less throttle for the same result. So there is a return on your investment.

I have MAF and got worse MPG, one of the V-10 guys took the end nozzle that directs the air from the grill into the filter box, cut and extended it, grafting a section in it, claimed to get better mileage, I lost the link to it tho. K&N has a new air box for the 97+ vans, if one could put a scoop on their hood, this snugs to the hood with a gasket when closed, you could really utilize it, I just won't pay $400 for it. What you need is to duct air into the box, be it from a hood scoop or piping from below the bumper, remember, dry air or rain will soak the filter media decreasing intake.

I know someone who hydrolocked his 5.8 with that stuff, twisted a rod locking it up real good.

look here Aircleaner

or like this..

all homemade....

Sweet setup!!!

Those won't work with a MAF system though.