Near steering firewall insulation

I'm in the proces of removing all the original firewall insulation (as per the book; it's only sound deadener).

I have one piece left; which is sandwiched between the steering plate and the firewall.

As you can see on the picture, I loosened the 2 nuts holding the plate; but it is not moving.  This plate is plastic; so if I pull/twist any harder with a rigid putty knife under; it will break.

Any idea how to loosen this plate so I can remove the last piece of insulation behind?  I see a bead of clear silicon holding the plate down as well; wondering if it's from the previous owner.  My last resort is to cut around and just leave it there; a little bit sandwiched under.

Bonus question; there was a total glue-fest on the top left firewall area (near the headlight switch) to hold a little of firewall insulation; I really don't feel like removing it all; if I sand it with 40 than 80; would that be enough for the new glue to hold on too when I stick my new insulation (I will be using reflectix).

Thanks!

http://www.VetteRegistry.net/member_uploads/6401_6500/6425/P1000591.jpg

You are going to have to loosen the steering column at the support hanger.  Might give you enough movement in order to slide the rubber out. But the rag joint may stop you short.  The bolts actually go thru the rubber. so that may be more of an issue.  You may have to loosen the rag joint  at the steering box so that you can move the entire column back about an inch.  This would also entail removing the nuts at the  firewall bracket.  The firewall insulation usually comes in one rubber backed peice. So i take it that you are trimming around each firewall mounted device.  Just a heads up that this could create places  where Hot air seepage  cac occur, so be sure to seal the joints with tape.  As far as the OLD Glue goes, you may have a problem with the new glue sticking if the Old stuff is silicone based. A roughened surface is better than none.