The best thing for you to do is get one of Pre 68 Daves water pump adaptors to raise the water pump higher on the engine.It uses a early 235 or 216 water pump and puts the pump near the center of the rad.He sells them on E-Bay for 40.00 bucks.I've got one on my engine and we just put one on my cousins "new" engine and they work great.
Pete
