350 Q exhaust manifold removal 1968 31 Commander salon.

I need to remove my riser and exhaust manafold to change out my starter on my port engine. Can anyone tell me if the coolant drains on the riser will drain enough of the coolant to remove the exhaust manifold? How much coolant can I expect? I assume the drain on the exhaust elbo will take care of the raw water….let me know if I am wrong .