Well CNCzone used to be my favorite, but it seems that it has gone way to IDK commercial, add orientated, like I was happy with cnc zone and was on it everyday, like 15 years ago, now well, really I'd like to find other forums myself. They all seem to be manual machining orientated or like you said, geared towards the professional.
That being said, doing a cnc conversion, even from scratch, mechanically, is less complicated than most of the RC bits we assemble and play with on a daily basis. LOL, I did the conversion of the mill with a 4 inch grinder and 3-d printer. Just to say I did. 5 thou backlash on z and no discernable on x and y and it will run at 200 inches a minute. But I did start with good models in Solidworks and just made it up as I went.
The 8x14 lathe will be even easier, but it is like 120 degrees out in the shop, so yeah that project is on hold till it cools down sometime in november. The 7x12 I will keep manual.
I am going to redo the z axis ballscrew mount on the mil as I hate the idea of the 5 thou backlash even if it can be mostly eliminated in software.

Let me know if I can ever be of assistance on a cnc project or you need suggestions and such.