Mark I had the 1835 cc VW and also have the RAF48 wing, so take with a grain of salt: Once the static port was accurate, stall power on was 49mph, power off 52mph. Anything under 60 and it was really mushy and about half the response from the controls as above that. I found my Vx climb to be 85 mph but engine temp rose quickly, so only good for first 400-500 feet or so. 95 to 100 mph was best cooling climb and Vy or best rate.
In the pattern 105 to 110 mph on downwind, base first notch of the belly board 25 degrees slow to between 95 - 100 mph, final at 3/4 mile last notch of 50 degrees belly board, and slow to 85 mph. This made for a steady as rails approach, even in wind. Roundout in the grass before the numbers it slows immediately to 80, holding it in ground effect about 2 feet off and it slow thru 75 to 70 and begins to settle. Slight back pressure to just kiss the mains, and as they come on between 65 - 60 mph, "roll on" the forward pressure to hold the tail up, and let it slow by itself. Depending on the wind it will separate from the runway at between 65 and 75 (and weight). This may change with the Corvair but not much. All else does not rely on the engine but mainly CG, weight, and configuration. Also, I leave in idle power plus a couple of hundred rpms. This also helps to stabilize the glide and prevent shock cooling of the engine. Colin
