Cleveland heads...?
 

Are there differences in the water passages between the us cleveland heads and australian heads, to be specific are there a few more holes for better liquid transfer? I have heard yes from a machine shop but would like to confirm it.

I have not heard this. boss 302 heads and cleveland heads have a different water passage but I have never heard of this problem and I doubt it is true since swapping Aussie heads is a common occurance and I have never seen it mentioned. None the less, since it is a common swap, even if they are different there must be a relatevely easy way around it.