Agreed. If it was separate tickets and no checked bags I may feel like taking a gamble and doing something that short - and in most cases it would be fine. But with checked bags I wouldn't do it. I am assuming you would have to bag drop at T3 no later than 60 minutes, so realistically you have 55 minutes to do immigration, collect bags, and get over to T3.

There is no conformance at T3 so at least on that point you would be ok.