This MAY have come up before but i couldn't find it in the search. The E36 dash kit that you can buy takes up the 2 top slots, then what would you do with the climate controls?
you think anyone will come up with a bezel for the climate control that is square.
I doubt there is much call for it to be worth while.
The original front just clips off, so making a mould of it and then fibreglassing it to make it square shouldn't be that difficult.