Id like to understand what the most profitable way to fix up a current 1,700 SFR in a 6,200 sq. foot lot would be? The lot goes from street to street. Plan would be to sell. 
1. Keep existing building ($850K appraisa...

Always keep an eye on interest rates to optimize cash flow and return on equity. if you switch to long term hold investing, you'll want to see if equity stripping is a strategy that works for you. 

After 20+ years, I hear from so many who are more motivated by fear than optimism and make decisions based on not losing rather than a high probability of winning. 

@Nick Am Setting up a management S-Corp (LLC-B) to manage properties owned by your LLC (LLC-A) can provide tax benefits like retirement contributions, payroll tax optimization, and deductible expenses (e.g., home office, health insurance).

I’d love to hear your thoughts on whether this approach makes sense or if there are other strategies you’d recommend to optimize profitability.Thanks in advance for your advice! 

I have done BRRRRs in Milwaukee for a decade+ and if I am not on the job 2-3 times a week, things go sub-optimal.

Without more info this sounds like a less than optimal deal.

Work with a qualified intermediary and tax advisor to ensure compliance and optimize your strategy.

I also let Facebook optimize the ads for me.

Buying in this way can weather cycles for optimal timing to exit and 1031 or refi with low debt.