Boat engine

Hi all. I just had a motor rebuilt for my boat it's a 470 MerCruiser. its not a Chevy but for my question it doesn't really matter. Top half is a Ford 460 lower is mercruiser, and the bell housing bolt up is Chevy!

The machinist that did the build has 40 years experience and well known in my state esp for building race engines. So I'm not doubting what he told me, just wondering if there is a newer better sealant.

so my block has a slight nick in one spot where the head gasket will sit.
It couldn't be tigged, as would have to shave off more metal etc. machinist reasons over my head.

so he said clean up that spot really good and add a dab of rtv when setting gasket, and I won't have any problems. I'm sure it will work but I really don't like rtv. The nick isn't near the cylinders, it's where the lifters are, metal . I'll get a picture later if necessary.

So reading online " the right stuff " by permatex sounds much better, it seems more pliable, sticky, and permanent. Wouldn't I be better off using this over
RTV for a tiny spot like this? Temp wise I think it's rated up to 500 and over 400 continuous. Can't be used with gas.

Any reason not not to use it?

Thanks