One of the issues I ran into was the donor Manta nose was from a 1974 which has large aluminum bumpers. The tubes for the bumper mounts run parallel to and blend into the frame rails further back. This meant the frame rail would need to be cut further back than if a small bumper nose was used.
The main rail opening is just about the size of 2 1/2" x 2" angle iron. I ground down the edges and now have sleeves to insert into the opening which will support and align the nose during fitment.
I made the first cut on the wagon near where it would have been for an early bumper nose. This allowed for a more accurate final cut.
The final cut was made on both sides, roughly 1/2 inch back from the rear skid plate mounting hole
Passenger side cut line.
I used my engine hoist to support the nose piece for the initial alignment.
Next up, do a rough alignment and then check with the fenders.