Heating upstairs

[kybaseball]

I have a older home and use an OWB. It is about 5000 sq ft. very little insulation. I have 2 floors we are heating the first floor with the owb and keeping if 74 just fine upstairs is at 66. Both floors has its own air handler how could i get the pipping to go up stairs to heat the top floor? Need to know like what kinda pump will push it up there.