I definitely wouldn't target any HGTV style rehabs with structural problems or even plumbing or electric that needs updated. 

And quite frequently we are doing near guts these days, with all new and permitted electrical, plumbing, cabinets, counters, flooring, etc.  

Who can help me identify the plumbing and perform full installation?

Flooring, plumbing, new roof, added a garage, new counter top in the kitchen, full bathroom rehab including toilet, vanity, tile, redid drywall throughout, added a new cement patio, new cement sidewalk around the home, new drainage & grading.

I had one we inherited who did maintain the building & I needed him until I got familiar with the idiosyncrasies of a run down 6500 sq ft conglomeration of 6 apartments added over 30 years & a myriad of wiring, hydronic heating & plumbing that seemed to go no-where.

My experience being a licensed plumber in NJ, I can design plumbing systems up to 3 family before a engineers license is required on plans.

;)The Plumbing, Electrical, and everything else was original, and the 15-20+ hours of mild headaches I got dealing with the tenants at the end of 2019 was the last straw.

We're fixing roof leaks, broken doors and windows, leaky plumbing, knob and tube wiring, non-functional bathrooms, landscaping - the whole nine yards here, over time.

The joists should be easy to sister, other than removing & resetting any plumbing/electrical.10.

My thoughts are at the end of the day it's my property and I'm making sure repairs are being completed correctly which I had a plumbing issue as well that was fully repaired and normally I would not been at the property as much.