the links in the first post are funny, the first refers to the reggie jackson camaro and says a 600+ 454 inch LSX. 454 cubic inch is traditionally referred to as a 7.3L, not 8.3. A typo? the 2nd link however says a max displacement out to 511 cubes, which is 8.37L. Asking the bore and stroke is definitely a valid question. Sounds more like marketing and hype though, like they're looking for the biggest displacement number they can get away with publishing.
The LSX block is probably available in various deck heights, the 8.3L one being pretty tall.
The 454 and 502 run 4.25" and 4.466" bores with 4" stroke.
If the LSX were to use a 4.25" bore, it'd need a 4.5" stroke to make 511 cid.