18436572 I thought you were running that XE262H Camshaft in your 327 ? Also if I remember right you have Stick so your engine can Idle a bit Higher and maintain that 17" Vacuum easier . Now the same set up in an automatic tran's Truck in drive in traffic will start to Load up and it will be hard to maintain that 17" vacuum . Vortec Heads are a good Performer for the Dollar . But they need some mods done to them and Springs . Also folks talk about how well they Flow on the intake side . But not much is said about their Flow on the exhaust side ? When you over cam a Street car you will know right away . Then you can always install a Vacuum pump or Can ?