Removing the firewall isn’t a hard process, just takes patience & some accurate rivet drilling. Replacement firewall parts are readily available from Vans.
You may choose to also remove the front deck (in front of the w/shield) for easier access. When the firewall is off, closely inspect the floor panel & rib angles for buckling or cracks, Center mount brackets, & corner weldment mounts for damage or any related deformation in the longeron (usually shows as a bulge about 1foot aft where the longerons normally bend a bit down & inwards).
Another thing to look for- early RV6 used a 3piece firewall (2 narrow aluminum side pieces & Center stainless steel panel) depending on the builders original build dimensions, the replacement one piece firewall panel may require a bit of adjusting to fit in the old space. I can’t remember if the new replacement also comes prepunched which won’t match the original skin rivet hole placements. Also, make life slightly easier by ordering ALL the angles/spacers/aluminum Center mount brackets that go with the firewall panel!
Good luck - a bigger job than it looks!