The FE blocks with the main webs that will take the 427 cross bolted caps are common in the ‘64 & early ‘65 model years, but with that said, good 55 year old FE blocks are getting harder to find every year. Because it’s easier to add the cross bolted mains to those blocks they can get a little premium on the price for people who would like to do that modification. The downside is a ‘64 model year block will only have the early two bolt motor mount pattern. The C4AE-A blocks were used for both 352 & 390 engines. Like any FE block, it should be sonic tested these days before building, it’s not expensive. There’s nothing special about a C4AE-A block that would make a solid 4.13” bore likely. Best practice now days is to keep the cylinder walls as thick as possible for best ring seal anyway.