My 81 stock block and 76 celica head detonates under light loads!  There's no reason to use the 22r intake manifold either, the 20r manifold breathes a little better if I remember right.  You can get an adapter from LC engineering to run your 22r carb on the 20r intake too, if that's the way you wanna go.  Power is definately better on top too, it'll pull atleast another 1000 rpm if not more over the 22r, depending on your setup.