In this case, if you need to make a decision fast, assume it is essentially going to be a new build inside with all new wiring, plumbing, mechanics, framing, drywall, trim, etc.If you assume this, and then learn you can salvage things, you are in a better position. 

Typically mine go out on 3 day weekends when I’m out of town or on Friday evenings along with water heaters, appliances, garage door issues, and occasional toilets and other minor plumbing issues.

I believe the plumbing and pumps will cost another $3,000 once he’s at that stage.

The house is about 60 years old so wear and tear on the plumbing(underground) and other structural concerns have me worried that keeping it once my new house is built will be a mistake.

From plumbing and sewers to electrical to foundations to framing, roofing, insulation, and so much more.

You can even create your own out of scrap lumber, but whatever you do make sure your cabinets are level and plumb.

What this means, however, is that the domestic manufacturing base has to be hollowed out. 

It is usually difficult and expensive to physically separate meters/plumbing on existing older properties, but is the best way to do it.

It also makes the plumbing and electrical easy as it is all exposed. 

Scope included building a couple walls, some light plumbing work, and a high voltage electrical wire for a dryer.