Unless you want to go to an Asian, Indian or Middle Eastern airline, in which case they will probably not only require you current in the NG but current in their colour scheme, i.e Must have flown a white/blue/green one in the last 90 days.
Sure, if you can fly a 300 you can fly an 800 and vice versa (Boeing went to great pains to ensure this would be so) but try telling some anal retentives!