This is an easy swap. I've done it a couple times. However, each time a new Holley 600 was used. I would always get a intake gasket set for a 340. I never used the end gaskets, just a bead of silicone. Each time, we were able to just bend the 318 throttle bracket over a little to get better alignment with the carb. (Not too noticeable.) We'd always have all the parts ready to go and we'd joke that we (a buddy of mine and I) could complete the swap on a running car before the engine even cooled down.