[Jeff Lee]

You can have a full interior roll cage (provided it is built according to the rule book). In Stock, no bars can be forward of the firewall.
I would cut the bars at the inside of the firewall, cap them with a 4" square plate and bolt the four corners to the firewall. Ideally you could sandwich the firewall with plates on both side but that may be a grey area. Somebody will chime in.