IF you are gonna race in the Northeast Outlaw 10.5 class (Cecil,Atco,Ultimate Outlaw Series,Shakedown 10.5)let Kenny put a full tube in it that will still be legal for that class. It will still retain the firewall and a "stub" of the original frame rails.

IMO, you need to first answer which class you want to run in, and then build the car to that.