For better or worse I'm attempting to correct the issues with the gawd awful repop core support sold for 68-72 GTOs.
I hope it works out since if it doesn't I'm out about $300 including shipping and will have to find a decent OEM piece which would probably cost $500 by the time it gets to my house.
Starting with modification to achieve the proper 9-10 degree forward lean at the top.
I took pictures as I went along and these are the results.
Pictures first .... then caption below picture.
Mount core support to a straight and level bench using spacers that fit inside the bottom rail .... this is the way the support would be mounted onto the frame. This bottom rail remains level and horizontal the to the ground when installed in the vehicle.
There are six spot welds on each side in the lower corners that need to be drilled out ... marked by the silver dots in these two photos.
This brace has to be cut along the silver line ... I used a plasma cutter.