I tried something similar with a pair of H4 LED units I bought last year. I couldn't get the light coming out of the high beam side to have a nice cutoff like the low beam side.
I used to think that it would be easiest to manufacture the same reflector design (mirrored, of course) and just mount the bulb in a position that made it focus differently. This theory was further supported by the fact that the back of the reflector for the high beam side was much thicker (~4mm vs 10mm, if memory serves). However, offsetting the mounting collar by the same amount (or not) did not produce any usable light pattern.
I have since blacked out the lower half of the dipped beam emitter (as you can see in the picture). I'll refit these units and report back. Another candidate is the Nighteye H4 LED with the shields on the lower beam emitter.
The trouble is that you need to remove the front cowling (with the reflectors) to comfortably experiment with different positions for the optimum beam focus. You need a target surface a long distance (50-100 ft) away to try different emitter positions, ideally in the dark.
OneWizard, I have very similar units to the H7 LEDs mentioned above. Mine have solid heatsinks, but the emmiters, housing and drivers look identical. I got the tightest beam aiming at a wall about 40 ft away, by rotating the bodies in about 5 degrees. I don't think it works too well out on the open road, though.
Please stand by for some photos of beam patterns with a non-ideal target surface (my street)...