the stock wiper motor was vacuum powered off the engine vacuum.
If you watch ebay and search new listings every day under 1934 1935 Chevrolet you should have one fairly soon. Might have to be rebuilt and not sure who does that.
Or place a wanted ad in this sites "parts wanted section" down the bottom area.
The other alternative is to purchase a boat motor electric wiper motor on ebay thru various sellers.
Speedway motors in Lincoln NEB. one of the sellers also offers them with wiper arm and wiper. Plus a special switch just for the wipers.
A right side PASSENGER wiper was an option back them.
mike
1935 Chevrolet standard series 3 window coupe
1935 Chevrolet standard phaeton
1935 Chevrolet standard roadster