Gas was expensive (I think about $.75/gallon) as these were the Carter years, around 1978. 

So tanks are presumably full now. 275 gallons each.

We're not talking getting BOSCH ranges and appliances or 100$ gallon paint.

If more than a gallon (maybe more?)

From experience I'm not convinced on the air purge method.Instead I use a 3/4 HP submersible pump in a 5 gallon bucket & pump fluid (usually the pink 'food grade' RV anti-freeze) through the lines.

When I buy a rental house now, it's just like going to the store and getting a gallon of milk. 

I hate white walls and didn't mind doing the work to get rid of them, but I wasn't going to spend $40 gallon on the paint I would have put in my owned home

Do you think one 50 gallon water heater would work for 2 units?

Go a day ahead of the exterminator with a giant box of thick 50 gallon contractor trash bags and make sure the tenants but everything in plastic boxes or double tied up trash bags (be careful when you get back home).

@Samuel Glantzyour market is not that expensive compare to Hawaii.try this 2 bed single family lower rent is $1500- $2,000.Price you will not find 2 bed less than 500k..i mean never.That's the reason i want to come to your town and invade your city.loli have in-laws in Peoria....i love it there...gallon of milk there is from $1.99 to $3.Here in hawaii $9.00 to $11.So i'm coming to your friendly neighborhood.Thanksjoe