Engine noise identification help ?
 

Hey guys, new to this site wondering if anyone can help identify this noise in my Chevy 2003 350 small block in my boat.

my boat overheated due to a stuck thermostat and the valves mushroomed on me.

I have already done the following but still have this noise.

- Replaced the thermostat (which was stuck closed)
- Removed Heads, had heads machined and stainless valves installed.
- Replaced Timing chain set with original GM parts
- Installed new plugs
- Drained and re-filled the oil.

Any help would be appreciated.

If it's upper engine, I'd say lifter or rocker arm