The 5 3/4" lamp with H4 bulb is not large enough to provide you with anything more than minimum (legally adequate, not necessarily adequate in reality) light. It's a small lamp, and only about half of its optical area is used to collect and distribute light on low beam, effectively cutting its already small size in half. The original reflector/lens is notably inefficient, but this fundamental limit is is the case no matter what reflector/lens unit you use, and whether it has the optics in the lens or in the reflector. If you have room to install the larger housing shell that accepts a 7" round lamp, you then have a clear path to install any of several different good 7" headlamps that will provide much better, safer lighting performance. If you must keep the existing housing shell, and you won't accept the LED lamp's appearance, then the best upgrade (though it will probably seem counterintuitive) is to install an automotive H5006 halogen sealed beam unit. It produces more light than a same-size H4. Note that any automotive 5 3/4" lamp will have three locating lugs on the rear face of the lamp's rim, rather than the single lug on the Harley lamp, so you'll have to make three corresponding notches in the seat ring of the bike's housing shell to acommodate the automotive-type lamp. This is the case only for the 5 3/4" setup, not for the 7".
