One thing not to forget is that you must have the code to move from EPROM to SRAM in some kind of (EP)ROM. I suggest that you get some faster ROM rather than trying to fit a square peg into a round hole. In the early days of "C" I had to do what you want to do because an early "C" compiler insisted on sticking data storage in between code segments it was such a kluge that I almost cried. If you insist on doing the ROM to RAM, do it in assembler using MOVC and MOVX, but you will still need to start in ROM for the transfer code and you must for that time adapt your timing to the ROM and when done how are you going to speed up?

Erik