I'd probably do that if i was MTL.
Not sure where Firstov will fit but he's 21 with indefinite rights like all Russians RFA's drafted currently do.

Greenway is a less player then Dvorak but i like his style its like Andersons.
But i think Spacek would make up for that better then Firstov if you're not adding picks .
Dvorak is a top Faceoff Center good for Bulk Defensive draws and that has value even if we have to wait 1-2 more years to get it .

Greenway , Firstov and a 3rd
Or
Greenway and Spacek

Spacek is a non-starter in a Dvorak trade.

Firstov was drafted out of the USHL and is currently on the first year of his ELC so everything you just said about him is incorrect.

Christian Dvorak is an average third line center that's not worth anymore than this.