I don't recommend shaving the head more than is necessary just to true it up for a street rebuild.If you cut it enough to raise the compression ratio to a level that will actually make HP that you can realize,you get into another can of worms.The more you shave the head,the more you retard the timing,making it necessary to install some type of cam gear to adjust the cam timing.Then,with the increased compression you need more cam,carb,ignition,gearing,ect.It turns into a viscious cycle.Unless you are planning to turn your 2.3 into a hot rod,I wouldn't shave it more than .020".This is just my two cents worth.