i did the head 3 years ago.Me personally would check the head and block with a straight edge. If it looks good slap a head gasket on it and call it good. I wouldn't doubt if the head bolts went torques properly. I bought a brand new 4k blueprint gm 355 and blew both head gaskets and when I took it apart to check my 1/4 inch impact took out most of the head bolts. They were not torqued properly at all.
I agree but planned on full disclosure, used boats are a hot market item right now.. selling for 3x normal value.I think I'd do the due diligence in making sure it's not going to blow another gasket prior to selling, if you're not going to tell them about it.
Don't be another reason why people are weary of buying used toys.