I have a Parker 275 [No 36].
The two in my keel are different, one M10 and the other M12.
I have had a shackle fail which resulted in the keel dropping, not something one would want to subject the boat to unnecessarily. This indicated how difficult it is to visually detect crevice corrosion/fatigue in stainless [the photos are on the forum], so I would recommend that if you are in the process of messing around with the keel, and don't know their history, you replace them.
When I took the keel out to blast and re-coat it, I replaced mine. The threaded holes in my keel are quite deep, and there was some increased play around the top of the threads, weighing up the options, I elected to put studding into the holes to nearly full depth, and used Wichard eye-nuts on the top. This gave a respectable safety factor for both M10 and M12 sizes.
There are pros & cons to the different materials one could use, in the end I decided to use 316 stainless for the studding and the eye nuts. I used a little loctite on the studding in the keel, but a lot of sealant around the hole entry and under the eye nut.
If your size is M14, then the normal DIN eyebolt/eyenut break load is more likely to be adequate, the Wichard eyebolts/eyenuts have a higher capacity than the DIN standard.
I now use 8mm Dyneema [D12 type] for the hoist line. Mine has an electric winch in the forepeak. The second eye nut has a wire pennant with an eye for a pin to secure the keel in the up position. The keel lowering indicator line also comes from this pennant.