From what you say is that they are not legal to be there based on today's zoning (non-conforming), but they are legal based on when they were installed (legal).

I have installed a mailbox and address numbers.

That's not a 'bad' rate to borrower very accessible capital that has to be repaid over a generous 360 installments. - Most DSCR loans come with standard 3-5 year early payoff penalties.

If it were mine, I would have the same company come out that did the install and refurbish the area back to its original condition.

I'm looking to install a new furnace in my duplex in Cincinnati OH. 

Depending on the facts and circumstances of the agreement, it could either be treated either1) the sale occurs as of the original agreement date, and then your taxable gain is generally spread out over the life of the principal payments as an installment sale (although I should mention any depreciation you've taken on your property could affect this), or2) the sale does not occur until the lease option is exercised, and gain reported at that time.

@Tucker Cummings after struggling with SMS Marketing (and Wordpress plugin), and Slybroadcasting not having all the functions I wanted, I was just about to set up a Mautic installation on Digital Ocean when I came across REI Reply. 

In this case, the material cost AND install costs will vary, so having an idea before you even meet the contractor is important.  

It would involve installing new dedicated water pipes per unit, three combi water heaters (to replace the two conventional water heaters and the central boiler), and three gas and water meters.

Repair & installation costs in the Boston area are some of the highest in the country.- Watch out for residential tax exemptions, and be aware of which towns / cities have them.