Cash flow could be a wash or slightly improve while appreciate potential would surly get better w the SFHs.

At $712,500.00 New loan that would put you at 75% LTV on a 3 Unit I would assume so your good there and rental could be used if it was used to wash the mortgage payment going traditional. 

I have a tenant with a boat and a race car in a trailer , another tenant that brings home his Kenworth tractor ( no trailer ) to wash and wax it and do some repairs .

They hang great on the beds, look awesome and wash up great.

Where is the laundry located in those homes?

Your repair budget won't survive one modestly poor tenant turn, but your vacancy is a bit high so that could come out in the wash.

You won’t pay cap gains tax but you’ll pay some recapture tax on depreciation, but the amount you’ll pay tax on will match the amount of depreciation you deducted while it was a rental....basically a wash.

Add the en suite laundry, nicer sinks and appliances!  

Anyway I have about $135k available on my heloc. sale price on the duplex is $279,000, so 20% is about $56k. the house is perfectly livable as-is, but at $60/sqft and properties on the block selling for $140/sqft i think there is room for some forced appreciation. the building is currently a three-floor duplex townhouse, one unit is the ground floor and unit two is the top two floors. all floors are basically the same floor plan. the second floor has a kitchen/laundry stacked above the first floor kitchen/laundry. on the third floor, the room is in the same place and empty, but utilities (water gas electric) are already run and in place for adding a third kitchen/laundry, so conversion to triplex would be simple as installing cabinets and appliances and building an exterior staircase up to the second floor rear deck. the three 2bed/1bath units would rent for $1000-$1200 a month each, conservatively. we would have to find somewhere else to live for that to happen, but that is our 1-3 year goal anyway. would it be better to make the bank loan smaller with a bigger down payment from the HELOC?

This will give you a general idea of availability of rentals, price points, demand for rentals (based on average days on market), what's usually included with rentals (heat, laundry, parking and etc) and more.* Run the numbers.