I2C generally expects the pullups to be about 1ma in strength. (Like highlander, there can be only 1, so if your cards have built in pullups, disable them and install 1 set on the bus signals)
This means the ideal starting value for pullups on the 3V Nano would be 3300 ohms or 3.3K. Ohms.
If your wires start getting long... drop down to 2.2K