So I'm looking around for engine pics for my 65 Belvedere wagon. I am putting in new heater hoses. Problem is that I've found pics with the heater hoses going either way. Manifold to #1 nipple at firewall and water pump to #2 and vice versa. The only difference is that one is a 273 and the other a 318 poly. I wouldn't think it would make a difference. What is the correct way?