Local codes may vary. May depend on the year built as it would be grandfathered. I would point out the hazards and the limitations of use and recommend consulting with local code enforcement as to OK or not OK.
Definately a NO GO on a bedroom up there, Or below if the furnace is not enclosed, with outside air for combustion. The 70's were real big on lofts and ladders to "HIGH" places. Whats the year of the home?