They are precisely made to specific Fel-Pro gasket sizes.
What makes them unique is that they are double sided.
One side is actual size for the head and intake. One side is .050" smaller for making an "anti-reversionary" step on the intake. The dowel pins precisely locate the template.
Port matching can be done with a gasket as a template, but this is a much improved way. I'm a fanatic for details like this.
Don't try and straighten this hump by grinding. You'll break into the pushrod hole before you make it a straight shot.. You can see I just cleaned it up and squared it off. Not too bad at this stage, but it could be better.
Look at the Dart Sportsman II head in the first (color) picture. The unported intake port looks much better, doesn't it? The Sportsman design moves the pushrod ever so slightly away from the port. Not enough to cause valve train problems, just tweak some of the kink out of port .
A lot of work has gone into solving this problem on various aftermarket head configurations.... GM finally eliminated this issue on the new third generation (LS1) of small blocks.
Be VERY careful not to nick the seat. Do port work before the valve grind. If you polish the chamber, use an old valve to protect the seat.
Best way to try your hand is on a cheap set of heads. Do one port and take it to get flowed. See if you made an improvement. Once you get a good port, you can make templates to duplicate it on the other seven. It takes about 2 to 3 hours to do one port properly. Count on 40 hrs to do a set of heads.
These pictures are for "Reference Only".