well... we cant just say it's a myth by looking at the size of the motor... i used to be a big honda head and one thing we honda heads really know is that anything b-series fit on anything b-series... you can pull the head off of a GSR (1.8L) and put it on the block of a CRV(2.0L) or you can take the head off of a SI (1.6L) and put it on a LS (1.8L) or a CRV (2.0L) so the real question is ... is the head on the miata the same as the head on a protege? are parts interchangable like they are with the FS-ZE? is it the same engine series? are the block similar in every aspect aside from cc's?
it would be cool if they were interchangable... or if some sort of hybrid can be made... like miata head on protege block??? up the compression a little???? i dunno...