Fastest/ most powerful slant six?

http://www.moparmarketforum.com/forum/viewtopic.php?f=9&t=6131&hilit=turbo+tilleys

This engine is in a 66/67 Valiant in Australia, owned by the Tilleys and car has been around for a long time. It isnt set up for the drags but has still run in the 10's over the quarter at around 127mph roughly from memory.