Hey, when I switched to wood, I used a batch file for the conversion but that stuffed my saves, sorta, it made the sav file like this: thisisnotarealrom.nds.sav.sav.savRupeeClock said:Your save data will be intact, you might just have to change the file extension.
Whatever firmware you used before probably uses .sav for save files.
Wood R4 firmware will use .nds.sav, so just rename "Mario.sav" to "Mario.nds.sav" and you're good to go.