The 5.0 truck intake would be an upgrade but as mentioned it won't fit on a 5.8, there was a company making adapter plates at one time but they cost about the same as a complete Typhoon intake and the injectors would not be optimally positioned any more so I'm not sure it's a good option.

 

That's good to know. Thank you to both of you, xlt4wd90 and Conanski, for the information. I think I will stick to the Typhoon upper and lower intakes. I don't know what they will cost but I have all winter to collect parts so I can spread the cost out over time.
I haven't shopped around for the intakes yet as I'm still looking for GT40 heads. All of our junk yards get picked over almost immediately when a Mustang or Explorer comes in (at least that's what they have been telling me.)
I'm going to presume that, if I can find them, they will cost $100 to $200 each and then $400 or $500 each for rebuilding. Total cost may be $1400 to $2000 for heads complete?
If that's close then I might contact Ford Racing to see if they offer a GT40 head with a mild configuration to fit my needs. I see they offer them new but primarily for racing and the cost is pretty close to what I would pay for getting and rebuilding a used set of heads.