Keep revving it- - - - -pretty soon you'll be able to look through the big hole in the engine block and you won't have to do any disassembly. I'd suggest disconnecting one spark plug wire at a time to see if the noise changes with the ignition disabled on one of the cylinders. You've got enough valve clatter from seriously out of adjustment valves that it's masking the other noises, but there's still a noticeable hard knock, either main bearings and/or at least one cracked piston. You can use it for a boat anchor before too long unless you start doing some serious diagnosis. Too bad- - - -it's definitely salvageable right now. Once it starts throwing pieces in all directions it won't be!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!