I've got a bored out 327 with stock cam, Q-jet on a stock manifold, stock distributor and coil, and cyclone headers. It was partially restored in the 1980's but has sat a lot recently due to job, family, and lack of dinero. I've have recently rejuvenated the restoration and have it running on the weekends. I have noticed a little irregularity in exhaust sound from the right bank and there seems to be some negative pressure at the right tail pipe. This side also has a significant backfire on decelaration at both high and low rpm's. Vaccum pressure gauge reading at the intake is 22 at an idle but has small regular drops to 17 or so. Think this is a sticky exhaust valve or similar problem. I do need to have the carb reworked, ignition and plugs repaced to eliminate them as a cause. Any other suggestions, ideas, or advice before I pull the heads?