Edelbrock Air Gap intake. How are your heater hoses plumbed?
Same deal on my 65 Barracuda 340. I just noticed you said the problem with the passenger side boss is that its hole is smaller. I don't remember having to make that hole bigger for either of my two small block intakes. I just used readily available fittings for the heater hose and the bypass hose from the intake to the water pump. ???
