Do theese engines run? If so, and you're wanting to sell them, I wouldn't disassemble anything. I'd clean up the outside a little bit, and leave it at that. Used equipment is usually sold "as is". If you advertise that the engine runs, and for some reason, after you reassemble it, it doesn't, or the head gasket breaks, carb gasket leaks, or anything like that, you'd be hard pressed to sell anything ever again. A reputation will follow you almost everywhere. I've sold engines before and did nothing more than blow the dust off them.
That's just my opinion. I, personally, would not buy a used engine that looks like it has never ran. I would leave the cleaning up to the buyer.