I'm planing on replacing the timing chain and gears on my 67 standard and figure I might as well replace the water pump while I'm at it. Looks like both aluminum and cast iron pumps were used. I have not ID'd mine yet. Are they interchangeable? I was looking at pumps on WCCC and the pumps they sell as reproductions look to be generic to me. Does anyone make real reproduction pumps with correct markings?