Vigtavuori N340 is slower than unique, but faster than Accurate #7 or Longshot. That should work out just fine.
My Sierra manual shows a maximum charge of 6.8 grains with 230s. This should be around 900 fps.
My Hornady book shows 6.7 as the maximum charge at 900 fps, so I'd say this is solid info.
Have fun, and load safe.
