Flipping, Budgets and Electrical

[Jay Coolidge]

I bought my first flip home.  The home was built in 1920's.  I am currently in the initial stages of cleaning the property and getting quotes on the work that is needed.  Plan on putting in new HVAC, flooring, windows and redoing the bathrooms and kitchens.  One "behind the walls" improvement needed is wiring.  There is some knob and tube on the property.  The breaker box was updated in 2017 to 100 amp and all the wiring the kitchen was updated but because the knob and tube wiring to the rest of the house was left in the walls with updated wiring in the basement to the breaker box and all "new" from the breaker box to the knob and tube wires seems to be connected with a junction boxes.  I am not an electrician but getting a crash course in all this.

I've had 2 very different electrical quotes and plan to get more.  What was originally a smaller project could be much larger.  So here's my question, for those of you doing flips have you kept the existing knob and tube wiring in houses or do you generally rip it out and upgrade to new wiring?  

I was not planning on doing a full rewire. This will be a budget killer, but from what I read knob and tube can be safe under certain conditions and it also can be dangerous.  Since this is a flip and the house has not been regularly maintained for years I wonder how well the original wiring is holding up.  So that's my dilemma, let me know what you think- thank you!