Welcome man !

There can be lots of reasons why you walk your cousins truck , plus he's got that crappy VVT , but these 5.3 s run strong !

As far as lifters , you might get away with not changing them , I would try .

I put a cam in a 183k 5.3 , it ran fine for a couple weeks then one of the lifters started ticking . But it was a larger more aggressive lift and springs than your going to run , I say try it.

 

Ya that sounds like a stock cam.

 

Ya, I was thinking of trying without changing lifters, but figure that this way I could clean up the heads a little for a little better flow.