If the plates are simple 'bar' and have no welding alterations, etc. then plain 316 will perform to the same level as 316L.
wkeenan - Just imitate the same shape and size of the OEM plates just change the materials and surface finish. If you have had 'failure' then of course you can increase the 'cross section' of the OEM plates. Dont totally reinvent the wheel, just make the old wheel 'better' - small steps of improvement.