This "deal" will probably go just like those phony job postings that still float around. "Oh, I'm looking to hire someone to send my money overseas for me. You deposit this cashiers check into your bank account, keep your cut, withdraw the remainder, and then wire it to my guy Boris over in Belarus."
When the cashiers check turns out to be fake (and they are usually laughingly easy to spot if you know what you're looking for), the bank dings your account with an NSF and you're on the hook to reimburse them for the full amount.
So no, don't even entertain this guy. Send the first check back to him if it does arrive, and move on to another buyer. Preferably one with a PayPal account.