Upgrade 10.2.0.4 single instance Database and Convert it to RAC 11gR2

Hi All;

currently we are running single instance database 10.2.0.4 on RHEL 5.5. now we required to upgrade this to 11gR2 but in RAC. Grid infrasatructure. currently single instance database is on ext3 file system. but as new requirment we need to have cluster file system to upgrade and migrate it in to RAC 11gR2 (11.2.0.3) but OS will remain same RHEL5.5. i need to you kind and best advise from which step i need to start.

1- i should start with single instance upgrade to single instance 11gR2 (11.2.0.3)  and then convert it to 11g RAC. as we are using exsisting BOX in which we have 10gR2 database and will only add one more box to convert it into RAC.