Default Frozen at Samsung SIV logo. HELP!?

Hey Guys. I've had this issue before and can't remember how to get past it...

Wanted to get this S3 working for my wife, so I went into CWM and did a wipe and factory reset. Since then,
It's stuck on the Samsung SIV logo....

I've downloaded the stock ROM from sammobile but am reluctant to flash due to the 50/50 as read on here....

I've been in this boat before.... but can't remember how to get out of it. It was done from within CWM before to get back in.
HELP?

Thanks
DSSKing