Being 74 isn't the primary reason - not having ridden on the street since 1968 is the major issue. Also, everything I rode before emigrating in '68 was on the left side of the street, had right-side, 1-up/3 down shift pattern and left side rear brake. I'd have a tough time learning the current layouts. Also, switching over to the US side of the street was manageable when sitting in the US driving position in a car, as there is a continuous visual reminder.