[Xellex]

Now that could be a problem! I only thought he used 2 jigs in order to work faster and not flip the studs every time.
I did alot of measurements of the exhaust ports in the cylinder heads, but it's pretty hard to fit a caliper in there and get a perfect reading. Also the studs can be old and bent, and you can't get a good centerline. I haven't found the exact measurements anywhere on the web.. Actually what I did was to measure 4 different heads (8ports) and take an average of those measurements.
What I thought of, as a solution to slightly misaligned parts, is a bit larger stud holes in the 2 small brackets/tabs that get welded to the pipe.