800 engine noise help

Here"s the PRoblem... now that its quieter I can hear a pretty good rattle/knocking/clatter sound in the lower end. Its not real loud but can be heard especially on the right side. Its mainly near the front of the engine #1 along the line of the cam shaft on the right side of the block. I pulled the wires off the plugs as I read in an ooold post that that can help determine if its a rod knock. The noise did not change at all with the spark plugs disabled. It is also still there with an increase in speed (just sounds like a faster rattle/clatter). I did drain the oil. its very watery in consistency and is somewhat black/grayish in color with a little gas smell. It had cracked heads and I knew it was getting some water in the oil that way and do not know how long the previous owner ran it that way.

What does a rod or main bearing knock sound like? Would bad cam bearings make that sound? What about the lifters? I"m thinking about trying some new 30 weight oil in it to see if it goes away.

and one more question... I presume I"ll need to take the case-o-matic cover off to get the oil pan off?

Thanks for any and all feedback and help.