Just thinking out loud here as I'm not the expert...on any of this, really. BUT, some of this conversation doesn't add up to me. I'm pretty sure you won't find a 5.2 later than 2002, or MAYBE a 5.9 up through 2003? Is the motor possibly a 4.7? Also, you can run a carb (with an aftermarket intake) on the 5.2/9 if you'd rather keep it simple.