Tunercat/CATS would be perfect, and I would totally go down that road... if it were 1/10th the current price without silly licensing.

The chips futurelec has are 48 pin tsop 90ns (wrong packaging and "slow"), unless I'm just not finding the page you came up with. I contacted a US supplier that may have surplus 50ns SO-44 chips that happen to be milspec.

Google shopping returns a couple of Chinese vendors that will sell small quantities of SOP-44 70ns chips. The OE 512k/4mbit intel chips were 55ns, but 70ns for the 8mbit version. I may order a few, they take paypal.