It has been a while but I don't recall any formal minimum speed limit for ejection whilst dual, other than the normal seat limit of 0/90.
With you on that, wiggy.
Somewhere from the back of my mind comes a thought that JP & Hunter 7/8 seats may have been "handed". Anyone remember? If so, it could be that the guns & rails were in matching pairs with an asymmetry on each that canted out the trajectory but had the seats mounted parallel in the cockpit. It's all many years ago and my ageing brain is unable to recall.
The other part of the vague recollection is that the seats may have had a second letter suffix that defined the side they were to be mounted? Anyone know?