Yes, you can use standard low-shank feet on your 27. There are sets of low shank snap on adapters with many different feet on eBay that cost very little, and many of them will be useful with the straight stitch machine. Some will not, because they're intended for zigzag stitching.
Evaporust is like a little miracle for these old parts, though. You might want to give it a try for cleaning up your corroded-looking feet, then follow up with a metal polish and wipe with a little oil before you store them.
Editing to add search results:
https://www.ebay.com/sch/i.html?_fro...et%29&_sacat=0