If your "estimate" works for you and your "high estimate" is still workable for you, then you can feel confident that if you use good project management practices that you can manage the project to somewhere between those 2 numbers at worst.

And if they are a hobbyist/part-time builder, then they should engage the proper professionals, i.e. a title officer, civil engineer, architect, contractor et al to assist in reviewing the project's feasibility.

Look for areas with solid rental demand, typically in Blue Collar America, where BTR projects are particularly appealing.

The entire project took around 3 months with EVERY square in minus the electrical( some added) being gutted and renewed.

Good luck with the project.

Yes, because Private Money infers that you are in a negotiable deal where your project can be outside the box and you can negotiate unique terms with a private individual - that - or a big box lender with strict rules and guidelines. 

How did they perform versus projections?

Depending on your multi-family interest, type of project and timing; I might have some interest, if you're open to that idea. 

. - Projects give us visibility on my projects- My CPA can easily access the reports for tax preparation.

All in all my project we are proud though we fought through Covid and interest rates and have exceeded original proforma..