Are you planning to take on another project like that soon?

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.

There are a multitude of roles, stages, and responsibilities for each and every unique project.

I would like to be prepared for a larger multifamily project. 

Just so i can do the preliminary analysis on the propertySecond: I'm finding it difficult to get a clear price estimate of the CapEx's that might be needed.

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

I am building my investment portfolio(duplex) in Ohio Cleveland, a few properties i have analyzed  with net cashflow  around $100 to $290 here is one deal I am analyzingDuplex generates $1590 income /month together,pu...

The markets that can help you achieve financial freedom (see the Dependencies above).Talk about over analysis.  

we did that except instead of renovating it we knocked the existing home down and built a new primary. right after we were completed we had $500k in equity as we acted as the GC on the project. 

For example, multi family is really good for being able to do a cost segregation analysis and accelerate depreciation.