To be very honest, porting cast iron heads is not a lot of fun. The stuff is hard to cut, hard to weld back in case you take too much off and it presents a few health hazards.
First some basics : protect the valuable stuff, meaning: ears, eyes hands and lungs.
Eye-protection: I have tried most safety glasses but a lot of the time you still end up with ^@$t in your eye..
apparently a large amount of foreign bodies ground (no kidding) out of sclera (the white of the eye) is metal that gets in after grinding because it gets into hair first en then in the eyes after while. I have found that a motocross style goggle ( they are not all that expensive either) and a head cover (BUFF works well) combines with vacuuming you head & face area afterwards kind of works.
Ear protection: you need it. I use Peltor ones that are quite comfortable and you can wear headphones in there as well. Having less noise makes it a lot more relaxed even though it can be a bit warm sometimes.
Hands: buy good quality mechanics gloves, a bit more expensive but it keeps you hands cleanable and protected . The most effective way to clean you hands seems to be to wash you hair with loads of shampoo. That, or surgical scrub sponges with very soft plastic ”hairs”.
In woodworking it is very important to reduce the amount of dust to a halfway decent level. Not only does stuff like MDF produce dust like mad when cut , it also reduces accuracy quite a bit as it gets mulched and causes router bits to burn and such. Furthermore some wood dust is only slightly better than asbestos for your lungs. Therefore no sane person would do woodworking on a regular basis without proper dust control. For metal cutting it is mostly considered all that is needed a brush and pail as you produce chips and little dust. As Caast Irn is so tough you end up having to do some grinding as some point producing iron dust and grind stone debris, a very nasty combination indeed.
Cast iron dust is evil. Due to the high carbon content you get black dust along with the metal particles and it agets everywhere and then it start to rust and stick fiercely to everything (yes everything). It is also bad for the lungs. So first you have to try to produce as less dust as possible. I tend to cut quite a lot with carbide burrs that produce chips (also evil, but less so) and try to limit grinding with stones and abrasive rolls to a minimum.
Secondly the dust needs to be removed constantly and directly from the place you grind before it can spread and cause grief. In addition to that it is a good idea (as in no smoking while spraying brake cleaner is a good idea) to use a good N95 particulate filter mask.
One of the more effective tools is a down-draught bench. So I decided to have a go at one.
It is very simple: basically a flat box with holes in the top. Build in sturdy 16mm beechwood and Fir.
I have to figure out out if the holes need to be enlarged for them to more effective. I Tested it briefly connected to a shop vacuum that was rather clogged but with an orbital sander at it seems to catch-all the very very fine dust very well. The larger dust just falls down and settles. General idea is to use the vacuum source for my flowbench with dust separation vortex ( Thinking about a Oneira Dust Deputy ) as a pre scrubber coupled to a final filtration stage , either a engine air filter or go the whole hog and get a HEPA one.
A further option that needs to be explored is to have a lid with a mount for an intake manifold. That way you can stand the head on the manifold and directly suck through the ports. I have done some preliminary testing and that seems to work well for the intakes