How well supported are the Olds engines anyhow? Chevrolet, sure, but Olds? And there's not really an abundance of vehicles still around with the front-drive longitudinal TH425 transmission. Looks like the TH425 was used until 1977, then replaced with a lighter-duty TH325 (no idea if that would be up to the task of lugging a motorhome around), then that had an overdrive added in 1982, and discontinued in 1985.
For someone from Norway ... I think you're better off with a European-sourced motorhome.