Exhaust manifold cooling hose routing

[thatsmrmastercraft]

My '77 Stars & Stripes has been repowered with a 1976 Mercruiser 302 Ford. The original 351 was left over winter full of water and became a mooring block. The repowered engine had the original Mastercraft exhaust manifolds on it until today when I discovered that they are the source of the water getting into the oil. I obtained the exhaust manifolds that came with the 302 from the previous owner. They are from a Skiffcraft cuddy cabin (I believe this is an I/O). The exhaust hose will fit with little modification and the front cooling line will fit without problem. My question is there are two hose fittings on the exhaust riser elbow. I have nothing to connect to them. Does anyone know what they are supposed to be connected to? Are they I/O specific and not used on an inboard?