To get the throttle pedal in the right position the original bracket needed to be removed, a bit of careful die grinding in a tight space removed the welds and have put that aside. The new pedal requires a new bracket as it needs to be positioned straddling the upper firewall and the inner wheel well.
Rather than fold up something out of sheet metal, why not spend four times as long casting and machining an aluminium part? My sand molds are still pretty crude but slowly improving, although I've discovered that somehow the sand still hasn't dried out enough and is still too wet. I think this is probably the reason for the porous castings, good enough for a bracket though.
The bit that sticks out sits against the sheet metal where the original bracket was welded on. The area looks somewhat flat at first glance but needed a compound angle and a bit of clearance to get it to sit right. The stud on top is double-ended, so it both attaches the bracket to the firewall and the pedal to the bracket. The two 6mm button head screws are installed from inside the wheel well.
It isn't very well finished as yet, would be nice to clean it up a bit more but then again you don't really see it.
This is where the top stud protrudes into the engine bay. The grommet above is blocking the original cable hole for now.
Bracket in place, giving a flat surface for the pedal and room for the carpet to sit as before. The bottom hole is tapped 5/16" UNC (same as the stud) for a cap screw.
With the pedal installed. I think my photography is even worse than my sand casting, you'll have to take my word for it that everything is straight and in the right place. Feels right and the pedal hits the stop just as it starts to touch the carpet.