Planning on laying hardwood flooring soon on entire 1st floor. Original house was built in late 1800s. Width of house is 25 ft. 3 sections, 1st section is original to house and ends on foundation, flooring is subfloor (3 inch planks), with gaps, 17 ft and relatively flat and level. 2nd section crosses over original foundation with entranceway (to be opened), vinyl tile over hardwood sub, 8 ft, and crowned at end of section (foundation) by 2 inches, slopes toward 1st section. 3rd section, same vinyl tiles over plywood sub, fully opens (steel beam overhead with one ft support columns on each end), 12 ft and level and flat to end of house - this section is the highest point level to the crown between 2nd and 3rd sections. Joist supports - 1st and 2nd sections, true 2 x 8, 16 inch centered. 3rd section, dimensional 2 x 8, 12 inch centered. Radiators on entire floor. What is the easiest way to install hardwood flooring over all sections?