cooling p***ages in heads 0f V150 loop charge

[mhazza60]

Hi all,
I have had overheating problems with my v150 60 degree 2 stroke in Adelaide Sth Australia
Model HE150ELEDM
I have replaced the water pump and about to do thermostats and temp switches.
My question relates to number of cooling holes in the heads.
The block has many holes, but my heads only have, (apart from bolt holes)
2 large holes (one thermostat and one on opposite end) and a small hole going to the top bolt.
Is this normal, as the service manual shows many more holes in heads to match the blocks?
WHAT HOLES DO CURRENT HEADS HAVE IN THEM APART FROM BOLT HOLES
Thanks
MHAZZA60

[boats.net]

Just has the inlet and outlet holes.