If you know the thread size, look for eyebolts or eyenuts+316 [A4] studding with a quoted break or working load. Typically a safety factor of around 6 on break load would be used for hoisting applications. Try Proboat or Wichard.
I have a 275, and the keel is about 320kg. When I came to work over my keel last winter I found it had one 12mm eye nut plus stud insert, and one 10mm eyebolt. I replaced the 12mm eyenut with a Wichard one, and the 10mm with stud plus Wichard eyenut.
I also changed from 6mm 6x19 stainless FSWR to 8mm Dyneema to the electric winch - so far I'm happy with the Dyneema - we'll see how it has held up at the end of the season.
Regards
Dick
Dick
Dark Star P275 No 36