Advice on suitable SRAM
For the flash I would take parralel flash chip from some 2000-2005 years PC MBs, newer have serial flash usually. They are rated at 70ns, so should work at 10Mhz easily.

For the SRAM - not much production left of 'vanilla' SRAM, check out Samsung site, they still have 10ns 3.3 and 5v parts with various widths and sizes, price range - up to 10$ in retail). Most of these are in SOIC package.

For the 'shadow' functionality you would need some sort of memory controller (they were produced, but probably hard to find these days), but in your simple case you might wire chip select to OR of first bits of address bus, be sure to select fastest logic chips for this circuit.