We do our share of porting.
The profile pics that fettig and FUB show are similar to what we make. We do not go as radically close to the water jacket at FUB's picture shows. But as those pictures indicate, you can't see most of the critical modifications unless you cut the thing apart.
Every time we have shown porting pics, someone always comes out and says how we did it wrong... but here is what we do, based on our goals.
There is a problem with the intake port, as we do not agree with the right angle at the apex of the swirl chamber going into the bowl under the valve. If the head is going to crack, and a hard-driven engine is more prone, it will crack into the water jacket at the intake port beginning at that right angle. We round out that corner... carefully. We make about a 3/8" radius.
We remove material at the inside radius of the exhaust. Some who do porting feel that the exhaust gases aren't affected by that corner. We disagree. That is exactly where the bottle neck is. You have to be careful removing too much metal around the valve guide on the exterior radius of the exhaust port, or you will have a very poorly supported valve guide with a greatly reduced heat transfer area. Exposing more of the exhaust guide also creates a heat absorption in the guide, which is a negative effect. So, removing metal from the opposite side of the bottleneck is a good idea. Also, if you make comparisons to the later exhaust ports, say in the BRM and CBEA, VW has taken steps to smooth and open up that inside corner. So, what we have been doing on the inside radius is vindicated.
Between the ALH and the AHU, there is a major difference in location of a water jacket. We found out early when practicing on AHU cylinder heads. If you match the port to the exhaust manifold and go straight back on the head gasket side, you will break into the water jacket. Basically, we match the port opening to the exhaust manifold, then angle up and over the water jacket. We remove only a little material over the water jacket at that point.
Also for both ALH and AHU, you have to watch out for the head bolt holes in the exhaust. If you were to grind straight back from a line that matched the exhaust manifold, you will break into the head bolt holes. We believe it is good practice to match the port opening size, but not very good when you break into a head bolt hole...angle your cut around the bolt hole.
On the intake, we open up the bowl and smooth the angles going back from the swirl chamber. If you think there is much room in the intake runner to remove metal, just feel the web between the two center intake ports. It's very thin.
For about 3 inches, the intake only gets smoothed up with very little material removed. We do not build a full race head, so we do not remove the swirl chamber. A swirl chamber cannot work unless there is turbulence, so some expectation of flow loss is mandatory, with the payoff that you are going to make a cylinder head that will work efficiently when cruising. That is our opinion.