I think you need 7.6.1 to read and write HFS+ partitions, you cannot boot from them untill OS 8.x.

http://download.info.apple.com/Apple_Support_Area/Apple_Software_Updates/English-North_American/Macintosh/System/Mac_OS_7.6.1_Update/Mac_OS_7.6.1_Update-NetInst.sea.bin