Boiler vs hot air furnace

[Jeff K.]

Hi BP friends. I had a heating question and was hoping to get collective wisdom on the following:

I just bought a 2 unit house with 2 bedrooms each floor. Total house is about 1450 sq ft.

Boiler to first floor (according to sticker) was installed in 1964 and not currently working. My HVAC guy said it would take some money to service to just test it and see if it works- so I figured we may as well just get a new one at this point and have a fresh start. All radiators on first floor look ok. He said cost for boiler and labor, as well as the updating of some parts related to boiler would be $3700. ( second estimate was similar)

Second floor boiler (hot water not steam baseboard) is newer and looks good, however there is a cracked radiator in Living room that needs to be replaced. He told me a new one would be $2200. We searched for used/ reconditioned but they are also expensive, hard to come by for exact sizes and matches, and need time and money to test before installing.

(I budgeted for this in my purchase price)

So I see 2 options:

1-replacing boiler and radiator:$5900

2-I thought of taking this opportunity to switch out the boiler only on first floor for a forced air unit, run the ductwork under first floor in basement, and use the first floor radiator upstairs. ( maybe I could sell the remaining ones on CL to recoup some money) I am waiting for an exact estimate but his first thought was in the area of $7000-$7500. Although it is more initially to do this, down the road I would not have to worry about the expensive radiators going bad. (I don't think I would ever add AC to this down the line even though this gives me the option.)

Has anyone ever switched boiler to forced air just for heat like this? Do the numbers quoted above make sense? Any other ideas or options? 

Any advice would be very appreciated!