Since the 5.3L crank and rods are identical to the 5.7 and 6.0, the current LS1 stroker kits will drop right in. I did not even have to clearance the block on my motor.
Just check on 5.3L piston fitment, that is the only thing I am not sure about.
Or again, spend the $350 to have the block bored out to 3.905 or so and use the entire stroker kit. I have seen the Eagle kits on Ebay and other sites for $1999 plus shipping. These include all the bottom end parts you need to assemble the small iron block stroker!