Flash Memory Help

The following chip has gone obsolete [AM29F040B-70JF-ND] (https://www.digikey.com/products/en?keywords=AM29F040B-70JF-ND&Site=US ) and the recommended replacement is the SST39 series by Microchip https://www.digikey.com/short/pnrqtz . However, the original booted automatically and the replacement needs to be booted manually. I don’t know enough about these FLASH ICs, is there anybody out there with some experience with this that might have some input?

Potential solution provided per below:

Alternative cross option offered: