Brent:
You are generally correct on the sequence/procedure on locating and cutting the sidepipe holes. The engine/trans must be installed and the sidepipes installed and correctly torqued on the heads. You need to check to see if the four separate sidepipes stack correctly (squarely and together) at their terminus when the sets are bolted up. If they do not, then you have some adjusting and possibly welding to do to achieve this square "stack".
You are also correct in how the hole itself is spotted. You must project the line of the headers and arrive at the correct point of exit. I used the centerpoint of the four pipe group and a pencil. The pencil is located in the center of the four pipe stack and this centerpoint is located on the inside of the body. Then locate that pencil mark on the outside of the body....this will serve as your initial locating point for the template. Locate your hole template so that the centerpoint mark is in the center. Using a fine point Sharpie, draw your cut line around the edge of the template, step back and judge the work cosmetically. When you are comfortable that it looks right, and double check the correct exit point of the pipes, you are ready to cut.
On these bodies, the best tool to use is an air saw. If you do not have one, they are available at very reasonable prices at Harbor Freight, Northern, etc. Make sure they develop at least 8000 strokes per minute, and use three 18TPI blades per hole. They will cut the aluminum like butter, and handle very easily. I will be happy to fax you the sidepipe templates. They came directly off CSX 3022 (the Kimble Cutaway Car) and will allow about 3/4" of space around your pipes. To my eye, anything larger than that makes the hole look too big.
Email me off line if you are interested in the template, and I will be happy to answer in detail any other qiestion you have regarding your Kirkham.
Bud
