[m+mhammer]

I did it 25 years ago. 36x26 2x6's walls new floor joist( you don't what to be walking on your ceilings) and rebuilt 2 chimneys. Got 4 bed rooms and a full bath. I used electric heat. At the time i had forced hot air furnace. I would have had to replaced the furnace. also would have had to find 18sq. and 24sq. area for ducts. I was pretty lucky because i worked with some carpenters at the station. Not cheep but cheeper than a general contractor. Got it buttoned up. Then took about 18 mo. to finished. Don't forget new electric panel and the heating system. Good luck either why. Mike