I just bought the 1701 (clock-wise rotation) and installed it on my 68 LA. The dimensions of the new pump versus my old 68-style pump are identical. I wanted to stay with the pre-1970 style water pump for ease of installation (radiator outlet/inlet, pulley alignment, etc). The machine-work on the Flow Kooler pump looks very good to me. The visible difference is in the front 'bulge' (rounded area on the front of the pump) and the impeller.
Since I haven't used it yet, I can't tell you how it works. I am using a 'big' thermostat that I got from Mancini (180 degree). I'm hoping that thermostat works, but I have read people having issues (on Jeeps) with the Flow Kooler units until they change their thermostat to a Robert Shaw thermostat.
The directions that come with the F.K. pump suggest changing your lower radiator hose to a stiffer, reinforced version if your current lower is spongy. I was going to use a Gates 'universal' lower hose or maybe cut my existing hose and use some pipe in between the pump and radiator outlet to address the additional suction capabilities of the F.K. pump.