b20b and b20z is hard to find. i got a P8R head which has 84mm combustion chamber. i thought i could find some b21a1 at wrecker. b21a1 is 83mm bore. 1mm difference isnt goin to hurt. will the the head fit b21a1 block? b21a1 come from 90-91 prelude si. 97+ CRV and 90-91 prelude...i doubt it will fit..since they're b-series engine. so what do u think?