I believe growing up in a family of woodworkers and handymen has prepared me for these challenges, as I've worked on many houses and projects before and helped build a rather gorgeous 3000 sq/ft log cabin starting from foundation up as a young teen.

At the same time, you can be improving your personal finance position to have a solid foundation for investing and taking calculated risks. 

The house is completely gutted and ready for foundation Sill replacement. 

Major foundation changes, plumbing, electrical, etc would likely be off-limits.

I’ve found a SFR that needs a lot of work: foundation, water mitigation, plumbing (and this is what I can see).

It is going to take some time for that market to get back to where it should be after the over development this is common in Multi and commercial development.. at least what I have seen over the years  lag time is  so long to get permitted what is wild is when you see buildings that stop before they are finished.I remember a day in Honolulu there were foundations all over the place and see throughs.Vegas still has some and one huge one on the strip still sitting there 11 years later.in Portlandia we had half a dozen were the big underground parking structures were built started to go vertical and financing was stopped.. those have in the last 3 to 4 years though finally been finished but they sat there mothballed for half a decade. 

If nothing has been done since the eighties it's probably not a bad idea to look at the roof, windows, foundation etc. 

They said that a modular home is placed on an actual foundation, unlike a mobile home.

It will provide for a solid foundation.

If I saw any signs of pipes, holes, or repairs to foundation I would get it scanned.