I haven't used that Sandvik grade before, but for an 80 Deg diamond on 303 your depth of cut seems too high for a smallish lathe. I would probably back off the Depth of Cut to .05 inch per side max (probably less) and increase the feed.
For Stainless lately I have been using a CCMT From Iscar Grade IC907. In 316 and 304 it performs really well. I am using a small CNC chucker lathe with a 5C collet and 5HP. In 303 You should be able to tear it up. In stainless my inserts recommend 660-980SFM with a .002-.010IPR feed. I would think you would be fine in the higher range of speed in 303, but I haven't had success with feeds of over .004-.005 for roughing due to my power and rigidity issues (1/2 shank tooling.)
Hope this helps.