Boat engine

Hi all. Just had my engine built by a local highly recommended machinist. 40 years experience and very popular with local racing community. So I trust what he is saying, but want to get other opinions on one thing as maybe there's a more modern or better substitute?

Engine is for my boat, called a 470. The lower is mercruiser, head is ford 460. Bell housing bolt up is xhecyChevy though lol. I guess my question brand doesn't matter.

There re is a nick on the block where head gasket will sit. He said it couldn't be shaven anymore or tigged, don't remember exactly but he said it's not a big deal.

He said clean that spot really well and put some Rtv there when you install head. And I'll never have a problem.

My question is, is there a better sealant for this than RTV? I was reading about copper sealants but struggling to find the answer as you normally have no sealant on a head gasket so the issue doesn't come up. RTV may be totally fine and he's probably used it in this situation for years, but wondering is there better
sealant now?

i don't like RTV, it doesn't even work well with oil pan
Gaskets. i know it has its applications though.

Granted this is a tiny area, but very important as the build wasn't cheap.