?? Or do I need a seven? I am looking to change my 11" to a duel Diaphram 8".

Which tall BBC valve covers?
I have the GMPP cast aluminum covers and a 7" dual diaphram with enough clearance to go to an 8" or maybe even a 9" if I have to.
Remember that the difference is only 1/2" between a 7" & 8", or 8" & 9"..

And although my Camaro has been modified to RHD, the booster location is identically opposite the vehicle centerline and at the correct height, AND I am using the taller SBC engine mounts.

http://img226.imageshack.us/img226/5760/heapsofroomao3.th.jpg (http://img226.imageshack.us/my.php?image=heapsofroomao3.jpg) http://img154.imageshack.us/img154/3875/assembly1866cw.th.jpg (http://img154.imageshack.us/my.php?image=assembly1866cw.jpg)