What? It definitely will NOT hold eight from the factory. Or in any configuration, really. I've heard of guys managing to cram 8x 2.75" shells in a tube and still manage to not get the 6th 3.5" in there, but it wouldn't work out that way with the shells I'm using. Maybe if you found the longest possible 3.5"/shortest 2.75" shells it miiight work. But you're walking a fine line at that point.
The VM tactical in Canada comes with the mag tube extension blocked at 5x 3" shells I think, as the gun is stamped as a 3" gun. Works out to 6x 2.75". (Though there's a letter from the RCMP confirming that it is in fact a 3.5" chamber receiver, and that running 5x 3.5" shells is fine. Which would get you the 7th 2.75". Can't remember who got it. DILLIGAF maybe?)
Edit: What Colin just said. Lol.