For restoration purposes it may be appropriate to drop below 1k but that also depends on the stone. ie I'd happily use a 220 grit Shapton GS but not a 220 grit Shapton Pro. The 320 Shapton Pro is only a little finer but works well on razors that need major work.
No idea if your 250 is appropriate for razors but you will know if you try it . ;)