It's a cool idea, but for the amount it would likely cost (and work it would take), I don't think it'd be worth it. I'd rather try swapping a powerstroke in, if it had to be diesel. Or a cummins.
That gas 5.4 is a good motor, and it's readily available. For less time and money bet You could have a pretty solid 5.4. Or even the V10. Both pull well, although 5.4 doesn't hurry.
Now if you have a 6.9 sitting around, and time/ money aren't a concern, it's a heck of a body style imo, so with the idi you could make it a simple, easy to work on truck that would last a very long time.
All just my opinion, since you asked. Sweet grab in any case love that body style (with the older grills like that; less flashy than the new ones).
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