New to 340 so I have questions
A-Z, If you are mechanically inclined, buy a Harbor Freight leak down tester and compression gauge, or similar. Check the engine for both compression and leak-down. Depending on altitude, a solid 340 should have ~170 PSI Cold Cranking compression and leak-down should be 10% for a well-sealed engine. The leak-down test will also point out the reason for leakage if it is >10%. Noise in the exhaust is an exhaust valve, and the same with intake noise. Lots of are coming from the valve cover indicates ring leakage.
I just did this on a friend's 440 that he was given. Leak-down was 10 +/-5% for all but #1 cylinder which had a leaky exhaust valve. it was at 20% leak-down so we will run it as is and see how it goes. Going into a /6 '67 FB Cuda, but boy will it need some suspension and brake help!