What are the diffrences between gpz heads?

What are the diffrences between gpz heads and the ltd heads?
If a port and polish along with a valve job is done on the both heads, wich one is the better performer?

If you are talking about GPz750 and KZ550H heads the KZ750H head may be better because it might have a smaller combustion chamber, if they are ported equally.Stock 83-85 GPz750 heads are a little better than stock KZ750 heads (and every little bit counts), but if they are both ported equally than the advantage disappears.

Rumor has it that the KZ750H head has a bit smaller combustion chamber, but I have not verified it personally.