I had one made at Clutchmasters..in So Cal.  Google for them, I guess.  Sent
them a stock clutch and they sent me a revised one for my racer to stand up
to 475lb ft of torque..Cheap, too.  I think around $125 for two custom
plates and new springs.  I bet they could easily do a Van clutch that would
pull wheelies for you..
  Don Hanson

PS.  Pegassus Racing, referred to in another post about fire systems...They
are really good to deal with..Got my fire system there, and many other good
parts, quickly and correctly and reasonable.
  Don Hanson