Although D70 does not support FP High Speed Sync.
You can do pseudo high speed sync. on D70/70s by putting a tape on the two flash contacts shown below;
Set your flash to Automatic or Manual and D50/70/70s to S or M.
This will get your to sync. to any speed (D70 max shutter spped = 1/8000s).
Of course, this is not Nikon's solution and may upset some people but it works and I like that too.