small block water pump

Replacing the 273 in my dart with a 68 318. I was gonna put the timing chain cover, oil pan and water pump on tonight. while comparing the two engines, i realized that the water pump on the 273 is different than the one for the 318. The 273 has the water intake on the drivers side of the engine, whiel the 318's is on the passengers side. however the intake needs to be on the same side as the 273 because the radiator (aluminum aftermarket) has the connection there.

Also, the 273's pump has a different bolt setup for the power steering pump, while the 318's doesn't. Does anyone know about the differences in these? i would like to get a new pump for the 318, but may just use the one off the 273.

Also, my gasket kit for the timing chain cover isn't correct, and i use silicone as a replacment for the gasket?

Thanks