Unfortunately the pictures seem too small, without enough resolution, to really get a good look at them.
I will say, there is a C4AE-6090-H 427 Low Riser cylinder head casting, that might be what you have. They were kind of the last version of the 427 Low Riser head, and had those valve sizes. I’ve seen casting date codes on those at least as late as August 1966, which are usually regarded as an over the counter service head, but certainly it could be possible they were used on something like a marine engine, but if they are those they are not specifically marine. Ford did have specific marine engines, lots of variations of those. Here’s a picture of that casting number from the Internet, see if that’s what yours look like. It’s possible there could be other styles of how the casting number is arranged.
