We've had some debate about that on another forum. I believe that, for the early TRs, the wipers were designed to come down parallel to the windshield frame on the RH side for LHD cars, and LH side for RHD cars. Of course with no automatic parking, you can leave them wherever you wish, but flat against the frame seems like the place to park them to me.
As I said before, there is no adjustment for sweep, except for changing parts. The sweep angle for a TR3 is given as 130 degrees, which you may be able to find marked somewhere on the big gear inside the motor. Or maybe the Lucas part number, which I think should be 738908.
Here's the diagram for the arm angle, from the Lucas 400e catalog. The LHD arms are P/N 742147, which is listed as 9.5" long with a 15 degree LH "crank" (angle).