just keeps coming back to the usual Amiga 1.3 boot screen.
3.0 / 3.1 boot disks will not boot on Kickstart 1.3. You need at least Kickstart 3.0 to boot these disks. Or get a WB 1.3 disk to boot on Kick 1.3.
The Amiga Forever versions might be copy protected, the 3.1 rom is.
No, it is not. Although there are binary differences between the original 3.1 ROM and the Cloanto ROM, my A4000 works perfectly with the Cloanto ROM. It's for an A4000, though, it will not work on a 68000 machine, it needs a 68020 at least.
The ROMs in Amiga Forever are encrypted, though. You need to run Transrom inside WinUAE to extract a decrypted copy.