I think we all need more information on what you're looking to do. Are you looking to make this monster charcoal, or gas? Mobile or stationary? Fixed Grate or Rotisserie? What are your technical abilities? I'd hate to give you advice and have you weld something important (like yourself) or blow something up.
Give the board a little more info on what you've got and what you're after and I'm sure you'll get lots of help!