well, I hate that I am turning this into so much of an engine building discussion, but I guess I need to explain.
You can interchange bottom ends on a lot of engines. I have a BMW M20 mill myself so I know you can do that one. In that case, BMW increased the displacement from 2.5 to 2.7 by lengthening the stroke, it was not necesary to change the block casting. Also, if there is enough thickness to the cylinder walls in the original design you really can bore an engine out for a substantail bump in displacement.
Conversions like this are posible with lots of engines from Honda, BMW, VW, Toyota, Nissan, Volvo, Ford...and even Mazda, its just that it doesn't work with the B6.
With the B6 the stroke was already quite long, and the cylinder walls too thin to simply increase bore. So Mazda chose to cast a whole diferent block with more space betwen the bores.
Anyone who tells you that they are going to put a b6 cylinder head on a bp is full of it.
Miata owners, at least here in the US, always swap the entire engine--call it what you will.
All this complexity is why I wanted to ask about the translation.