I begun this project in 1999 to create a liner from a bomber. Grief's fuselage only allow 2 abreast seats and a central aisle. So, just a few passenger and 1 or two cabin crew. IMO, this meant a Business or VIP or, perhaps, a Presidential plane. Between 8 passenger in seats to 4 with seats and beds, a meeting table, ...
I did'n decided how to address the power plant issue until last month: Turboprop
One requirement was global reach, hence beds, even for crew.
Underwing, extra large tanks. Tank "german shape" was mandatory.