Not being sure of what was done the first go round, having to warranty what I do paint, and being particular about what constitutes solid metal, if it were ME, I would strip it to bare metal and address the findings. Not knowing your preferred finish level, product choice (rustoleum or PPG, etc) or intended use, it is largely your choice of how far you go down the rabbit hole. If there is no obvious delamination or other such defects you SHOULD be able to scuff and go, providing any previous rust repairs were done satisfactorily. My take here is that rust issues are cheaper to fix before the paint goes on. Not just materials, but time expended. All considerations you must look at in reaching your decision.