Dave,
I'm using a V283 with my R-D1s. This 283 came from the last of the production batches (discontinued 2006?). The 283 shares a lot of features with the 285, including trigger voltage, if they were made at the same time.
The really older 283s did have high trigger voltages, but the laters one used lower trigger voltages and are quite safe for modern camera synch contacts.
One way to test the trigger voltage is to attach voltmeter terminals at the flash's contact pins. Firing the flash should give a reading of its trigger voltage value.
And heed the caveat about the R-D1s's flash shoe. A heavy flash like the
283 may not be good for the camera. The shoe is attached with just four tiny screws and a hefty flash might just yank it out.
Jay