If you spend the extra money up front on a licensed, reputable plumber to handle plumbing matters, you won't have a busted pipe, wet drywall, an annoyed tenant, and an exorbitant repair bill.

Any new plumbing?

Adding an additional kitchen sink, bathroom sink, toilet, and shower might be too much for the existing plumbing infrastructure. 2.

Old wiring, plumbing and almost guaranteed lead paint. 

Plumbing gets expensive quick though.

Here's how I would calculate Capex: total up all the big-ticket items that haven't been recently addressed (roof, plumbing, electrical, HVAC systems, sewer line, kitchens and baths/in-unit upgrades/appliances, parking area/driveway, landscaping/exterior, etc.).

Foundation and plumbing is already cost 12k.

Depending on the  need of any mechanical updates(electrical, plumbing, HVAC, furnace, etc), you might be able to get away for less than 20k.  

Some Inspectors will sign off on site, and others will make you remove enough drywall to check framing, electric, and plumbing.

The older you get the more you have to pay attention to: mechanical systems (electrical, plumbing, HVAC); roof; foundation; windows; rot/insect/termite damage; insulation.