Don't want to worry the OP unnecessarily... but aren't you guys possibly being a bit too optimistic?

Official Minimum Connecting Time between North and South Terminals is 75 minutes.

As I understand it MCT assumes an airside transit (and no checked baggage).

The OP's connection is 100 minutes.

Is that extra 25 minutes really enough to get through Immigration, collect baggage and drop it off again?

My recommendation to the OP would be have a Plan B ready... maybe even book an alternative flight if they're cheap enough (as they won't be cheap on the day...)