Engine trouble shooting

[DirtyDirty]

I have a bad rattle in my 77 spider I bought the other day. It's in the engine. Sounds like a tin can in there rattling around. It will do it for a few seconds then stop. But when it starts man is it loud. I only run it for a little bit to try to pin point the spot. I checked the cam bearings.checked water pump bearings. Compression is good( I thought it could be a broke ring). It smokes some on start up but stops after a min or so( bad valve seals I guess). I'm thinking now it could be the oil pickup in the oil pan that's broke or bent? Any other ideas? Thanks

[So Cal Mark]

there are no cam bearings in your engine. It could be debris in a cylinder. A broken oil pump pickup won't make noise

[DirtyDirty]

Oh well. I guess I'll be tearing it down then. Thought it might be a simple fix.