Can you tell us what the marking are on the right side, on the back of the block?
I meant to say the left side (drivers side).
410's are usually C6ME blocks, so it's doubtful it would have a 410 crank.
Blocks, in general, through out the FE years, can have quite a mix of sand cores, after 1960. The C5AE, kind of proves that. There is really no relationship between your block and a C5AE-A 427, especially since they had C5AE -D, -E & -H, 427 blocks. Before '60, they had a minimum cyl wall thickness of .170 for 239-292 (312 was .145), MEL & FE. Somewhere between '61 and '63, they changed that and from then on, they can be all over the place but, there are some closer standards for the 428 & 427. The 428's are ~.15, the 427's are ~.13 but, have a kind of clover leaf shape for rigidity. I have a 1970 dated 361 industrial engine (4.050 bore) that has (sonic test) cyl thickness, between cylinders of .259 & .184, the inboard and outboard walls are even thicker.
There are some patterns to wall thickness vs casting# though, your C5 block, may be a little thicker than some other 390's, that's why I ask for the space between the cyl walls but, even if it is a little thicker, if you want to bore over .040, you'll need a sonic test.