Update. I found a universal seal at Rubber the Right Way that works even though it's not the same shape as the originals. It's a "D" shaped hollow extrusion with peel and stick backing. The sticky side fits in the rail channel with a little tucking with one of those nylon trim tools. I'm a little leery of peel and stick but the adhesive is really aggressive on these so I'm hoping they'll hold. If they start to come loose I can always glue 'em with trim adhesive. I hope this helps someone else with a '55 Vic or Merc needing roof rail seals.
https://www.rubbertherightway.com/ex...-15692-ctg.htm