Role of a Machine Shop in Relation to Heavy Equipment

I apologize in advance if asking questions like this if forbidden or this is the wrong sub forum to post a question like this in.

I'm in soon going to be in the process of getting a building built that will be the shop for my Dad and I's farm equipment. But I also want to expand the machine shop to the point where I'd doing work for customers.

I like big machinery, so I figured doing work on heavy equipment would be something that I would enjoy and be able to make money doing. But I've been thinking and I figured ya'll might know the answer to this. But with part support and consumable wear parts, how much would a machine shop be needed for heavy equipment repair?

I have a POS Case wheeled excavator and the hydraulic pumps quit (Vickers gear pumps), so I'm remachining the central housing and bearings from Dura-Bar and bronze. If it works (never done it before), I figure I could rebuild (actually rebuild, not just change out wear parts) hydraulic pumps. But again this would only be needed if you were running an obsolete pump like I am and you can't get parts.

At the speed I move, it's probably a few years before I'm actually ready for customers, but I'm just wondering what parts if any are sent to a machine shop and how I would need to tool up to accommodate that.

Thanks for any and all help.

Role of a Machine Shop in Relation to Heavy Equipment