Using the info in the thread link below, it's easy to modify a non-A/C shroud for to be identical to an A/C shroud. I placed masking tape around the circumference with one edge where the edge of the A/C shroud would be and used a sabre saw to slowly cut along the tape. I then sanded the edge smooth.
http://67-72chevytrucks.com/vboard/s...d.php?t=446805