1965 Valiant Firewall questions?

All 65's have a depression in the firewall for the V-8 distributor, even if a slant. The firewall's on AC and non-AC cars did vary. What distributor are you putting in that won't fit? Usually a different tranny requires mod.s to the transmission tunnel hump in the floor, not the firewall. I kind of lost you on "remove & install" firewall and "remove floor panels". These aren't bolt-on parts like a fender, but extensively welded in, so I hope you know what you are in for. There are posts on drilling spot welds and welding in new panels. If your metal is sound, I would think that "cut and weld patches" would be the normal approach to gain clearance.