looking for shoulder belt attachment location

Thanks for the input guys!

I chose to fabricate anchors as per the photo below. The dimensions of the plate allow for insertion into the large hole and then 90 degree rotation.

Seat belt anchor.png

Fabrication steps:
1) The hole drilled through the plate must be 1/2" to accommodate the non-threaded part of a seat belt anchor bolt.
2) The five fender washers are held in place with a 1/2" nut/bolt to centre them during welding to the plate. The washers bring the finished thickness up to the level of the sheet metal.
3) A seat belt anchor bolt is used to hold the nut in place. Use additional fender washers on the front side to ensure the nut is tightened securely.

Installation:
1) The anchor bolt must be removed to install the assembly through the hole and then rotate it 90 degrees.
2) Re-install the anchor bolt so that you can hold the assembly in place to tack it. Remove for full welding.
3) I used fiberglass bondo to provide a clean finish over the plate area.