The thing is...and PRH already said the very thing I'm about to say just in different words...if you are careful and if you pay attention and if you don't get greedy, a guy in his shop, with a grinder HE is comfortable with (I refuse to use an electric grinder...I can but I don't like it...too dang big and heavy and when you are grinding for hours on end, the size and weight just don't cut it, plus I get much better results with an air grinder as I feel I have more control...but I digress) you can pretty easily get 85, maybe 90% of the results of anyone else.
It starts with the valve job (for me) and everything after that is based on that valve job. The throat, the bowl, the chamber. Once you have the VJ in, the rest is using your head, taking your time and not getting greedy.
A few nights after work and maybe a Sunday if you really want to put some lipstick on the pig and you'd be surprised what a guy can do at home.
One thing that always makes it tough for me (again, I'm betting PBR, PRH, MO and maybe even 318hasvalvethatwillflyandpokeyoureyeout can agree, except he does quite a few videos and stuff so he may not find this true) is I've done this for so long, and done so much of it, I do things and don't know I actually do them. For example, I was helping a guy shape some stuff on his heads. I did some of the work and then let him copy it. I told him what I use for tooling, but it's not the same for everyone. I use some burrs I doubt any one else uses because they are funky. As long as the result is the same, it doesn't really matter how you get there.
Anyway, he brought a head back over and wanted to see how I did got a certain shape. What I did I had no idea I was doing. I was actually manipulating grinder speed, tool pressure and angle without even knowing I was doing it. I could literally slide my thumb over against the little valve I was using to control the speed of the grinder without ever slowing down.
When he asked me about it, I was a bit shocked. I had no idea I did that. Had no idea when I started doing it. Have no idea how long I've been doing it. That's what's hard to teach. And the only way to learn it is to do it yourself. And you may never do exactly what I do or how I do it but you can still get the same results.
I was also only changing the tool angle when I was changing tool speed.
My point is that in head porting, like many other things, there are more ways than one to get the same results.
One of my best friends came by my house one night after work to use my flow bench. He never really paid attention to the tools and burrs I use to port with.
He looked at my stuff and said, and this is about as close a quote as I can remember from 2000..."what is all that broken, screwed up dull junk you are using to port with????" He couldn't believe what I was using. The next day I went and looked at what he was using. We didn't have single burr or tool the same, but it was hard to tell our port work apart.
Run your new heads for a year or two. Then pull them off, freshen up the VJ and do a little grinding. You can hit the 90% mark pretty easily, and rather quickly.
That last 10% is a real mother bear to do. To get that last 10% will take almost as long as the first 90% has taken you. That is when you are picking the fly poop out of the pepper.