What about historical appreciation rates?

Hello All,I am looking for special funding resources to complete the restoration and hurricane mitigation of a historic Key West home built in the year 1900.

Purchase price: $680,000 Cash invested: $210,000 Sale price: $4,000,000 Historic retail space sees new life as a flagship coffee shop after 30 years of vacancy following the closure of Doggie Diner.

Interest rates on the mortgages are very low historically speaking. 

I read some great historical posts on this topic but wanted to see if I could gain any insights in todays market as there has been a continued run up ( generally speaking....)Do you regularly evaluate your RE investments against a return on equity metric?  

I currently own a Quad and duplex in the historic district.

The neighborhood was a very sought after location (Renton Historical Hill).

@Cody L. indicated two $100K properties and I understand his rationale but I fear $100K still leaves you in a poor class area and so using similar rationale I would recommend a single financed $200K RE that is in at least C+ class (and preferably B class) area or do as @Brandon Burns suggested and partner.If you purchase a $50K RE OOS it will be in a poor area that has historically zero appreciation. 

You can look at historical data for appreciation in a metro area, but for a buy and hold property this isn't very important.

Some of these folks have a huge amount of historical knowledge and can likely tell you the history of the land.