I'd just buy the seals and glue them on. Quick way to figure out typical new seal/door fit issues most seem to have. If the seals work, buy that same brand next time. If not, use a different brand next time. Save the rust repair and other adjustments for when you are ready to do paint. In the grand scheme of things, the seal is cheap.
Your goal is similar to what I have done. A driving/restoration/keep it from getting worse until I do final work job.
