[Richard]

IMO do not see a problem. If original paint is not lifting there is no reason to strip. One thing the painter I work for (my friend) has done for his entire career painting over 40 years is to apply a non sanding sealer like thinned DP50 just before paint application. Wet sand primer or existing paint down to 500 or lower, apply sealer, allow to tack up then apply the color. He does this on every paint job. Bare metal job or over existing paint, single stage, two stage or three stage paint. Costs more but it is extra insurance for top coat to stick and anything under it to stay there.