[minime's 68']

I'm putting a 99' 5.7 Vortec in my 68'. I'm running into a problem with the Vortec Air Box. I need some advice on what I can do with it. I was thinking of just putting a K&N cone filter on there but I don't know which size. Please Help. Any Advise or Pics. Would be a ton of help. Thank you!!