It's a bit higher on the V11. Check this thread:
http://www.v11lemans.com/forums/index.php?showtopic=5121
Here's a discussion of valve specs- US, world, and Raceco
http://www.v11lemans.com/forums/index.php?showtopic=3235
This should REALLY be pinned in the FAQ section
I kind of quit following this one, but there are several options (this isn't complete). MPH cycles sells a complete kit www.mphcycles.com under V11 stuff. Williamsburg made or makes risers, I think cyclecat made some. I don't recall which company, but one set cracked on IanJ's bike. You might want to avoid that particular brand. I put handlebars on my bike. It was easy and cheap.
http://www.v11lemans.com/forums/index.php?showtopic=1061
Cheers,
Jason