Paul:
First off ask the dude, that makes the board you want to purchase, to give you some FULL vendor part numbers for some SRAMs he suggests will work in his board. The go get the DATA SHEETS for these parts, look at the package dimensions and pinouts. Then go to your part supplier. From him either buy the same part numbers as the MPU board manufacturer gave you OR find out what he has, get those part numbers, get those data sheets and do a little engineering parts selection. It is not a pile of rocket science.
Michael Karas

Or better yet!! Buy the board with the silly parts already on it.

Michael Karas