do you match based on lining up the mounting bolts with the gasket, then head, then manifold, or is there another more precision way?
What I like to do is buy a "blank" or "cut to fit" gasket. It might be ~$20.
Then you bolt the intake on the engine with a thin layer of RTV on the intake port side only around the ports.
Let it dry, I usually do this at the end of the day so its ready the next morning.
Then the next day you remove the intake and you have an exact imprint of the head ports on the intake.
I usually take a mechanical pencil and trace the imprint so when you start porting you don't loose the imprint.
Then you can port match it exact. When it looks right then I go by feel, you can feel how smooth it is by running your finger in the ports. I don't want any bumps if possible, just smooth curves.
I have been planning on making a video on that for years, I will do it this summer and post it.
The gasket match works, but many times the height will be a little off when you bolt the intake on because it depends on the block deck height, cylinder head deck height, port height, etc. When I use my method everything is as perfect as I can get it and it's faster for me.
Sometimes I have used cardboard before when I didn't have a blank gasket. I just made one out of that or just blank gasket material of the same thickness.
When done I discard it, the time it saves and the exactness you get is worth the money, especially if you are porting for a customer, but I used that method on my own stuff for almost 2 decades now. It's just something I started doing when I was trying to think of a way to get more accurate results, it worked, so I stick with it.
On my own stuff I just leave the carbide burr finish. But many customers like the 60 or 80 grit finish. It looks more professional, but I don't think it adds any power.