I know nothing about LS motors, I'm strictly a '67/'72 owner, but 4.8L was the later designation for the L6 292 cu in. 350 = 5.7L. So I'll guess 5.3 is 327 (or thereabouts). So did they make a 4.8L V8?
[I heard Ford in the '50s came out with a 292 V8 ( no relation to the Chevy 292). I have also heard the Ford guys consider a dog. But I'm very fuzzy on Ford lore.]
Here's a bump, at any rate.