Just mate the 2 together? I thought that I had to upgrade the camshaft, and swap out the 22R valves to the 20R head, port/polish the head, bore the block and bigger pistons...etc...etc... 
If you are wanting all the power avalible fron the 20 head on a 22r block then yes do all these things. If your just in for a little gain then just mate the tw0 together.
