One of my mates has a fairly stupid td42 with custom cams in it and it has worked quiet well. I haven't heard of anyone else doing it though you might have to get some custom one made up. His td42 made abit over 900nm at the rears.
ivan tigh (tigh cams) do a custom cam regrind but you need to supply the cam it was fairly cheap aswell but i cant remember exactly how much but i never ended up doing it plans changed
I looked at this too, but general concensus was do exhaust, boost controller, turbo, intercooler mods before you start digging around in the engine changing cams.
When I asked them Joel at PGS and Andy at Dieseltech here in Vic both agreed with this approach. A cam may boost power, but generally at the loss of power spread and driveability.