There aren't 64k SRAM in that package. The next common step up is the 62256. That is 32k and 32 pins.
The general format of part numbers for 8k SRAM is M6264PK-S
Where...
M designates the manufacturer
6264 designates 8k byte (64 k bit)
P is power (nothing for standard, L for low power, LL for ultra low power)
K is package (mfg specific, DIP, SMD, etc)
S is speed in 10s of nanoseconds (12 == 120ns, etc)
Based on the original part number you want something that is low or ultra low power, 150ns or faster, and SOIC package.