Parsons and Collins are the obv LB fits - guys who could start in the Van Noy role, then move to the Hightower/McKinney role eventually. Those are the only two I see as good Mike options, and I'm not sure Collins wouldn't just stay outside.
Baron Browning is an excellent fit for the Van Noy role, and I'd definitely keep him there (not even thinking about the possibility of moving him inside).
J. Davis and P. Werner are less obvious fits who could potentially bulk up and play outside. If Werner really bulked up, he could play the Mike, but that's a lot of weight to add.
At DE, Payton Turner is the really obvious fit. Oweh would need to add some weight, but he has the frame, and Paye is more similar to Lawson in build - just a lot more athletic.
There are a bunch of Day 3 guys who have the frame to play DE for Miami. Most just aren't very good.
I keep forgetting about Chauncey Golston, who reminds me some of Trey Flowers. Def a fit for Miami and a pretty good player.