How do we convert the radiators to something that is more efficient while the tenants are still living in the units?  

Basements aren’t counted in square footage even when converted.

Personally, I would focus the majority of my attention on perfecting my lead generation with the goal of converting these leads into buy-and-hold investments.

I've used to BP calculator several times, but am still not sure if I am doing it correctly. 2 bed/ 2 ba (however extra "den" can be converted into another bedroom)Asking Price: $169,000 ....

So converting to LTR is not an option for all of these owners. 

Only concern is people paying rents in during this virus, I may wait till the eviction ban gets lifted and convert into section 8 rents and increase rents.

If building can't be converted then have to build in demo costs to get to a clean slate again.No legal advice given.

The house was originally a duplex at about 1200 sqft, but was converted to a single family home by way of cutting doors into the wall separating the two units.

@Michelle Dong most of the MF units in Indianapolis are SFR's converted to MF in old rough neighborhoods.

One is a rental the other is converting to a rental now.