So I spent hours looking at cooling specs from 68-73 and it turns out that ABSOLUTELY my water pump pulley ratio does not add up to my modified 340 application. My pulleys are OEM from a 1973 318 engine and have a ratio of 0.95:1. According to 1971 340 spec there was this same ratio with NO AC however 1972-73years 340 spec have a 1.2:1 STD and 1.3:1 AC spec. So I agree 100% change pulleys however these pulleys are unicorns and super hard to find. I called a machine shop yesterday and turns out I can have a water pump pulley made 5" diameter which would give me 1.31:1 ratio. Cost is around $500 for this custom pulley. I'm pretty sure that 5" diameter will be ok after measuring it looks like the water pump will clear the inside diameter of the pulley. Would the milodon 8 blade high flow water pump need to be swapped to a 6 blade with this ratio?