Your pic of the floor/toe board combination is different than original. The original configuration involves a pinch weld (many spotwelds) of the flanges on the floor board and the toe board.
Though the replacement combo panel is visibly different than original, it is a better design, structurally speaking.
Trying to replicate the appearance of originality to that after-market panel would be a huge challenge.
Carl
I guess I will try to butt weld what I have (shown in another thread). If I screw it up, I will order the firewall.