As much as I hate to say this, something went horribly wrong with your clutch installation. Not only will the clutch not release because of this, much worse is the fact that you have wiped out the thrust bearing in your engine. This can be the only reason I can think of for the intense smoke coming out of the breather pipe.
Do NOT run it any further if there is any chance of saving the crank, which is doubtful. I would suggest dropping the pan and removing the cap that contains the thrust bearing to inspect for damage. And, of course, it will need to be split once again to see what happened with the clutch.
When you joined the engine to the trans, did you have to suck it together with the bolts?