I want to make a chatter bait out of an Owner Mambo jig head. I dont want to use a split ring. Is there a way to bend the eye of the jig out enough to fit a blade on? Heat it up maybe? Thoughts?

Split ring only works well with a jig with a horizontal eye.   Have you tried bending flexing it open with a pair of needlenose?   Did it just break?   I have tried bending heavy Mustad jig hooks to fit molds before and 9 times out of ten they just break.

If you heat it up red hot, you might be able to open it up, however when it cools, you will have hardened it and it may crack upon trying to close it.

Some hooks are too tempered to bend, some are easier.  Japanese brands are often tempered harder than others, so it's a crap shoot whether you can de-temper an Owner hook with heat.  If you heat it and let it cool slowly, that removes some of the temper.  Cooling it fast after heating creates temper.  All you can really do is try it and if it breaks or the lead head melts, throw away that jig.