[Richard]

I work for a paint and body part time myself. The one that did paint on my truck. No expert myself, IME see the 40 year owner of shop just wet sands and applies sealer to existing pant if it is not lifting or cracking. You could be opening yourself up to a lot of surprises and extra work (cost) by stripping to bare metal. An older Ford van in the shop now would be in the crusher if we stripped it. The owner would not pay to make the existing metal straight under old repairs.
Noting another post, flat finishes can be hard to apply even. A while back we redid a flat paint job on a 63 vette that had what appeared to be tiger stripes.