what does it take?

a friend of mine has a 98 gt, and has found a great price on a mark8 motor. it is a dual cam, 4 valve motor. what would it take to swap the 4-v heads onto the 2-valve motor, and would it be worth it to use these heads?

if someone has a link to a detailed swap, i would appreicate it, i am planning on printing it out for him.

thanks in advance guys.