It's very popular in Australia.... Many,many people use it in daily drivers as a stand alone or dual fuel system (along with both carb and EFI systems), and a bunch of people doing it in higher output situations too (not sure about all out stuff like you might be shooting for though off hand)
Might see if any of the Aussie members chime in, or try some of the Oz companies that deal in it alot...

I know a few guys with it in supercharged setups.
Here is a friends '67 Camaro with a blown big block on LPG..