RE: top flite p-51 giant scale build
Spitfire,
I always pin the firewall. Use to use wood dowels, but as of late I use left over carbon fiber rods. I seem to have a collection of left over short pieces that come in handy. As to the standoffs, I will have to let someone else help you since I am going electric. I fth e firewall is in the correct place you could simply cut off the "built up cowling and replace it with a fiberglass after market unit.
Mike